* MM-26203: Fix TestChannelStore//SearchAllChannels flake
Using random strings for channel names creates chances of collisions
when searching for specific strings.
We increase the search space increasing the size of the search string
to be searched. This reduces collisions and makes the tests more reliable.
For the "off-" family of tests, this probably needs more length. But
it would also need the tests to be changed slightly as the "off-" part
acts as a prefix. I accidentally stumbled upon it while running the test
50 times. Adding a "-" is probably good enough for now. We can revisit
if it fails again in CI.
* improved team_store tests too
22aff2af4a