[MM-320] Added config setting to enable/disable child pipeline notification

[raghavaggarwal2308]

Summary

When a pipeline with many child pipelines is triggered on Gitlab and the user has a subscription for "pipeline" in a channel, the channel gets flooded with many notifications. We added a config setting to enable/disable notification for child pipelines.

Screenshots

When enabled:

When disabled:

What to test?

• Not getting notifications for child pipelines when config setting EnableChildPipelineNotifications is disabled.

Steps to reproduce:

1. Connet your Gitlab account.
2. Create a subscription for "pipeline" in a channel.
3. Set up a child pipeline workflow on the project you have created a subscription for. (How to setup child pipeline)
4. Trigger the pipeline and wait for it to complete.

Environment:

MM version: v7.8.2
Node version: 14.18.0
Go version: 1.19.0

Ticket Link

Fixes #320

[codecov]

Codecov Report

All modified lines are covered by tests ✅

Comparison is base (7190bfd) 32.91% compared to head (6e8247f) 33.08%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #409      +/-   ##
==========================================
+ Coverage   32.91%   33.08%   +0.17%     
==========================================
  Files          22       22              
  Lines        4017     4020       +3     
==========================================
+ Hits         1322     1330       +8     
+ Misses       2564     2559       -5     
  Partials      131      131              

Files	Coverage Δ
server/configuration.go	33.33% <ø> (ø)
server/webhook.go	43.71% <100.00%> (+3.41%)	⬆️

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[AayushChaudhary0001]

Tested and approved
Working fine for both "True" and "False" condition, LGTM.