MM-23227: preserve disable across config changes

[lieut-data]

Summary

Fix an issue with how the configuration structure was always being reinitialized whenever a system configuration change occurred. Also avoid mutating the configuration in place.

Note that the go mod tidy commit was run on vanilla master, not specifically my changes. Not sure how that slipped in.

Ticket Link

https://mattermost.atlassian.net/browse/MM-23227

[agarciamontoro]

LGTM! Looks like the CI is complaining about the coverage, but I don't understand why.

[lieut-data]

Oops, yeah -- looks like the tests were actually failing. Fixed!

[codecov-io]

Codecov Report

Merging #93 into master will increase coverage by 1.4%.
The diff coverage is 33.33%.

@@            Coverage Diff            @@
##           master      #93     +/-   ##
=========================================
+ Coverage   16.24%   17.64%   +1.4%     
=========================================
  Files          13       13             
  Lines        1139     1139             
=========================================
+ Hits          185      201     +16     
+ Misses        916      900     -16     
  Partials       38       38

Impacted Files	Coverage Δ
server/command_hooks.go	8.72% <0%> (ø)	⬆️
server/configuration.go	51.33% <100%> (+10.66%)	⬆️

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[jfrerich]

LGTM!

[DHaussermann]

Tested and passed
I used the the user login event to be able to see when hooks are in fact disabled and confirmed I could repro the issue with previous release.

Tested and ensured that hooks now remain disabled when a new change is saved to the config.
Add a release test to cover this issue.
LGTM! Thanks @lieut-data for QA steps on this one.

Please merge.