test: align triplet tests with actual plugin behavior

Fixes CI failures from the prior commit's bats additions.
storage report mounts are prefixed with `-v `, logs.bats setup does not
auto-create the test app, the nginx-vhosts shell report emits JSON keys
without the `nginx-` plugin prefix, registry computed-image-repo falls
back to the default `dokku/<app>` repo name when no template is set,
cron computed-maintenance follows OR-not-override semantics so a per-app
`false` does not override a global `true`, the scheduler subcommand
help string is `Manage scheduler settings`, and bringing ps procfile-path
into the #8640 raw convention required updating the pre-existing
`(ps:set) procfile` assertion. Also extends fn-git-keep-git-dir to fall
back through the global property before the built-in default so global
keep-git-dir actually takes effect at deploy time.

tests/unit/scheduler.bats

@@ -17,13 +17,13 @@ teardown() {
   run /bin/bash -c "dokku scheduler"
   echo "output: $output"
   echo "status: $status"
-  assert_output_contains "Manage schedulers"
+  assert_output_contains "Manage scheduler settings"
   help_output="$output"
 
   run /bin/bash -c "dokku scheduler:help"
   echo "output: $output"
   echo "status: $status"
-  assert_output_contains "Manage schedulers"
+  assert_output_contains "Manage scheduler settings"
   assert_output "$help_output"
 }