sysupdate: Change feature/component enablement and disablement (#43191)

- sysupdate: In the auto-enable service, don't enable all features
    
    The auto-enable service should activate suggested components and
features but enabled all features which includes the default components
    unsuggested features and any unsuggested features of the suggested
components. This is unexpected behavior and we rather want this service
    to be limited to suggested features.
Switch the service flag to suggested and make the wording more explicit
    in the man page. Also fix the wrong statement that it operates on
    enabled components, it operates on all components, also explicitly
    disabled ones.

- sysupdate: Change disabling with
--component-suggested/--feature-suggested
    
    The disabling of features or components with the flag
--component-suggested/--feature-suggested didn't disable the suggested
ones but instead disabled all other ones. This is rather unintuitive due
    to how the flags are named and also not really needed because the
intended reconciliation outcome can instead be done by first disabling
everything and then enabling the suggested ones again which is easier to
    reason about. For components the tricky part is that they default to
enabled and thus it's better to have the disable/enable commands with
--component-suggested operate only on suggested ones instead of touching
others like "legacy" components that don't explicity say whether they
    are enabled and suggested or not.
    
    Make running disablement of components/features with
    --component-suggested/--feature-suggested undo a previous enablement
with the same flags. Document how one can align the system to only use
suggested components/features and not anything else by doing it in two
steps, first disabling everything and then enabling suggested ones. This
also makes it clearer now that all components that are not explicitly
    enabled nor suggested will be disabled then.

test/units/TEST-72-SYSUPDATE.sh

@@ -1717,12 +1717,20 @@ EOF
 assert_dropin "$(comp_enable_dropin compx)" yes
 test ! -e "$(comp_enable_dropin compy)"
 
-# 'disable-component --component-suggested' reconciles the other way around: it
-# acts on the components that are *not* suggested (i.e. compy).
+# 'disable-component --component-suggested' acts on the very same set, i.e. it
+# undoes what the enable above did. The non-suggested compy is left untouched.
 "$SYSUPDATE" --component-suggested disable-component
-assert_dropin "$(comp_enable_dropin compy)" no
-# compx must be left as it was (still enabled from above).
+assert_dropin "$(comp_enable_dropin compx)" no
+test ! -e "$(comp_enable_dropin compy)"
+
+# Reconciling the system with the current suggestions is a two step operation:
+# disable all components, then enable the suggested ones. Unlike the single
+# 'disable-component --component-suggested' above this makes the non-suggested
+# compy explicitly disabled.
+"$SYSUPDATE" --component-all disable-component
+"$SYSUPDATE" --component-suggested enable-component
 assert_dropin "$(comp_enable_dropin compx)" yes
+assert_dropin "$(comp_enable_dropin compy)" no
 
 # --component-suggested is not supported for the update verb.
 (! "$SYSUPDATE" --component-suggested --verify=no update) |& grep -F "not supported" >/dev/null
@@ -1816,6 +1824,12 @@ assert_dropin "$(feat_enable_dropin_default feata)" yes
 assert_dropin "$(feat_enable_dropin_default featb)" yes
 assert_dropin "$(feat_enable_dropin_default featc)" yes
 
+# ... and so does 'disable-feature --feature-all', in the other direction.
+"$SYSUPDATE" disable-feature --feature-all
+assert_dropin "$(feat_enable_dropin_default feata)" no
+assert_dropin "$(feat_enable_dropin_default featb)" no
+assert_dropin "$(feat_enable_dropin_default featc)" no
+
 # --feature-suggested (no machine tag): only the Suggest=yes feature is picked.
 rm -rf /etc/sysupdate.d
 set_machine_tags unrelated
@@ -1831,6 +1845,21 @@ set_machine_tags sysupdate-test-tag
 assert_dropin "$(feat_enable_dropin_default feata)" yes
 assert_dropin "$(feat_enable_dropin_default featc)" yes
 test ! -e "$(feat_enable_dropin_default featb)"
+
+# 'disable-feature --feature-suggested' selects the same features as the enable
+# above, i.e. it undoes it and leaves the non-suggested featb untouched.
+"$SYSUPDATE" disable-feature --feature-suggested
+assert_dropin "$(feat_enable_dropin_default feata)" no
+assert_dropin "$(feat_enable_dropin_default featc)" no
+test ! -e "$(feat_enable_dropin_default featb)"
+
+# The same two step reconciliation for features: disable all of them, then
+# enable the suggested ones, leaving the non-suggested featb explicitly off.
+"$SYSUPDATE" disable-feature --feature-all
+"$SYSUPDATE" enable-feature --feature-suggested
+assert_dropin "$(feat_enable_dropin_default feata)" yes
+assert_dropin "$(feat_enable_dropin_default featc)" yes
+assert_dropin "$(feat_enable_dropin_default featb)" no
 set_machine_tags ""
 
 # --component-all must still include the default component when all of its