fixes: lots of fixes for file descriptor leaks.

[pwhelan]

Summary

This provides fixes for many different file descriptor leaks that affect flb_reload.

Most of them seem to be related to mk_event_channels which were never deallocated.

---

Enter [N/A] in the box, if an item is not applicable to your change.

Testing
Before we can approve your change; please submit the following in a comment:

• Example configuration file for the change
• Debug log output from testing the change

• Attached Valgrind output that shows no leaks or memory corruption was found

If this is a change to packaging of containers or native binaries then please confirm it works for all targets.

• Run local packaging test showing all targets (including any new ones) build.
• Set ok-package-test label to test for all targets (requires maintainer to do).

Documentation

• Documentation required for this feature

Backporting

• Backport to latest stable release.

---

Fluent Bit is licensed under Apache 2.0, by submitting this pull request I understand that this code will be released under the terms of that license.

[edsiper]

@pwhelan since the changes are in Master (v3) and 2.2 branch, is it same to drop it ?

#8371

[pwhelan]

Yes, this is in fact supersede entirely by #8392 and #8393, therefore I am closing it now.