Add all tests to the gating plan

tests/Install/Install-test-of-grafana-package/main.fmf

@@ -12,3 +12,5 @@ recommend:
 duration: 15m
 extra-summary: /tools/grafana/Install/Install-test-of-grafana-package
 extra-task: /tools/grafana/Install/Install-test-of-grafana-package
+tag:
+  - gating

tests/Regression/bz1916083-grafana-cli-crashes-when-run-from-root-s-home/main.fmf

@@ -1,7 +1,4 @@
 summary: Test for BZ#1916083 (grafana-cli crashes when run from root's home)
-description: |
-    Bug summary: grafana-cli crashes when run from root's home directory
-    Bugzilla link: https://bugzilla.redhat.com/show_bug.cgi?id=1916083
 contact:
 - Jan Kuřík <jkurik@redhat.com>
 component:
@@ -13,3 +10,5 @@ recommend:
 duration: 15m
 extra-summary: /tools/grafana/Regression/bz1916083-grafana-cli-crashes-when-run-from-root-s-home
 extra-task: /tools/grafana/Regression/bz1916083-grafana-cli-crashes-when-run-from-root-s-home
+tag:
+  - gating

tests/Sanity/verify-systemd-units/main.fmf

@@ -1,5 +1,4 @@
 summary: Verification of systemd unit files
-description: ''
 contact: Jan Kuřík <jkurik@redhat.com>
 component:
   - grafana
@@ -10,3 +9,5 @@ recommend:
 duration: 5m
 extra-summary: /tools/grafana/Sanity/verify-systemd-units
 extra-task: /tools/grafana/Sanity/verify-systemd-units
+tag:
+  - gating