Write deployment context in init container

[kate-osborn]

Write deployment context in init container (#2871)

Problems:

• When running with N+, the first usage report does not contain the deployment context. The deployment context is needed in order to associate the instance with NGF.
• When collecting the info for the deployment context, it is possible to fail. In this case we send a report to N1 without the deployment context.
• The installation ID is the deployment ID, but it should be the Pod ID.

Solutions:

• When running with N+, write the deployment context to the shared volume mount in the init container.
• Use the Pod UID instead of the deployment UID as the installation ID
• Always set the static values of the deployment context in the nginx config. Static values include the integration and installation IDs.

[codecov]

Codecov Report

Attention: Patch coverage is 60.39604% with 80 lines in your changes missing coverage. Please review.

Project coverage is 89.71%. Comparing base (1ebaa55) to head (64f4214).
Report is 1 commits behind head on release-1.5.

Files with missing lines	Patch %	Lines
cmd/gateway/commands.go	50.57%	43 Missing ⚠️
internal/mode/static/manager.go	0.00%	19 Missing ⚠️
cmd/gateway/initialize.go	86.66%	4 Missing and 2 partials ⚠️
internal/mode/static/handler.go	50.00%	2 Missing and 2 partials ⚠️
internal/mode/static/nginx/file/os_filemanager.go	0.00%	4 Missing ⚠️
internal/mode/static/nginx/config/generator.go	75.00%	2 Missing and 1 partial ⚠️
cmd/gateway/main.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@               Coverage Diff               @@
##           release-1.5    #2905      +/-   ##
===============================================
- Coverage        89.86%   89.71%   -0.16%     
===============================================
  Files              107      109       +2     
  Lines            10997    11091      +94     
  Branches            50       50              
===============================================
+ Hits              9883     9950      +67     
- Misses            1054     1082      +28     
+ Partials            60       59       -1     

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