Demote unstable tests (#29250)

* [skip ci] Demote unstable tests
* [skip ci] Further demotions, fix artifact jumbling

e2e-tests/cypress/tests/integration/playbooks/channels/rhs/start_run_rhs_spec.js

@@ -6,7 +6,6 @@
 // - [*] indicates an assertion (e.g. * Check the title)
 // ***************************************************************
 
-// Stage: @prod
 // Group: @playbooks
 
 describe('channels rhs > start a run', {testIsolation: true}, () => {

e2e-tests/cypress/tests/integration/playbooks/channels/slash_command/test_spec.js

@@ -6,7 +6,6 @@
 // - [*] indicates an assertion (e.g. * Check the title)
 // ***************************************************************
 
-// Stage: @prod
 // Group: @playbooks
 
 describe('channels > slash command > test', {testIsolation: true}, () => {