fix(s3): start KeepConnectedToMaster for filer discovery with filerGroup (#7732)

Fixes #7721

When S3 server is configured with a filerGroup, it creates a MasterClient
to enable dynamic filer discovery. However, the KeepConnectedToMaster()
background goroutine was never started, causing GetMaster() to block
indefinitely in WaitUntilConnected().

This resulted in the log message:
  WaitUntilConnected still waiting for master connection (attempt N)...

being logged repeatedly every ~20 seconds.

The fix adds the missing 'go masterClient.KeepConnectedToMaster(ctx)'
call to properly establish the connection to master servers.

Also adds unit tests to verify WaitUntilConnected respects context
cancellation.

0 files changed, 0 insertions, 0 deletions