Update snyk branch monitoring automation

[orouz]

Motivation

snyk branch monitoring guidelines are as follows:

• main
• latest_major.latest_minor
• previous_major.latest_minor

currently we're only tracking main and latest_major.latest_minor, as previous_major didn't apply (7.x is irrelevant for cloudbeat)
as of 9.x, we need to monitor:

• main
• 9.x (latest minor)
• 8.x (latest minor)

Definition of done

• modify bump-version workflow to account for monitoring new relevant branches

Out of scope

• other changes to bump-version will be handled in separate issues

Related tasks/epics

• Workflows updates after 8.x branch-out #2492

[orouz]

one more thing to note about the bump_snyk_branch_monitoring step in bump_cloudbeat.sh is that the workflow runs on a branch, and the snyk step is meant to be global. this is because snyk doesn't let us update existing target, so we delete everything and re-import evertything. so currently if we do this just for a single branch, it'll override the previous one and we'll be left with either 8.x or 9.x