Reduce CNTi's slack channels to just one, 'cnti'

[martin-mat]

As per decision by TSC on CNTi Governance call on 2024-07-11, reduce slack CNTi's channels from 6 to just one, 'cnti'.

Current CNTi channels:

• cnti-bestpractices
• cnti-certification
• cnti-general
• cnti-testbed
• cnti-testcatalog-testsuite
• cnti-testsuite-dev

Target CNTi channel:

• cnti

Additional aspects to be considered:

• choose best mechanism to do that considering keeping current audience. Seeing number of subscribed members, 'cnti-testsuite-dev' has the most members (26), so perhaps rename this one to 'cnti' and obsolete remaining 5 channels.
• before removing old channels, do proper communication (cnti maillist, messages on old channels) and give reasonable time to subscribers of old channels to move.

[martin-mat]

I propose following steps:

1. rename "cnti-testsuite-dev" to "cnti" (can be done now)
2. post an announcement about slack channel reduction to all current channels (can be done now)
3. delete all "cnti-*" channels except "cnti" (after 1 week after 1./2. is done)

[lilluzzi]

Another option is to create a standalone Slack channel called "CNTi". This way we get out from under #lfn-tech channel. Most projects have a standalone Slack channel

[lilluzzi]

Steps 1, 2, 3 are completed