Update references to the archived slack room #support-client-plat

[sourcegraph-wk]

This batch changes references to the archived support-client-plat slack channel to now reference the support-frontend-dx channel.

replace "#support-client-plat" "#support-frontend-dx"

QA steps:

CI passing should be sufficient these changes are documentation changes.

_Created by Sourcegraph batch change Workiva/update_slack_channel_fedx._

[aviary-wf]

Security Insights

No security relevant content was detected by automated scans.

Action Items

• Review PR for security impact; comment "security review required" if needed or unsure

• Verify aviary.yaml coverage of security relevant code

  Questions or Comments? Reach out on Slack: #support-infosec.

[kimlarson-wk]

@Workiva/release-management-pp ready for merge.