chore(ci): cleanup gke related scripts

[czeslavo]

What this PR does / why we need it:

• Removes unused deploy.go script and Makefile targets
• Turns cleanup.go into cleanup_gke_clusters.go with a single purpose of being used in the cleanup.yml workflow
• Removes the concurrency property from workflows as it's proven to not work well in our case (it doesn't allow queueing more than 1 job, more on that in the discussion). In order to mitigate the possible issue with clusters being deleted by the cleanup job before E2E tests are finished, clusters are considered orphaned after 1h from their creation (instead of 30min).

Which issue this PR fixes:

Part of #3378.

[codecov]

Codecov Report

Base: 73.8% // Head: 73.9% // Increases project coverage by +0.0% 🎉

Coverage data is based on head (6fb829c) compared to base (6d755ef).
Patch has no changes to coverable lines.

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #3399   +/-   ##
=====================================
  Coverage   73.8%   73.9%           
=====================================
  Files        113     113           
  Lines      13896   13896           
=====================================
+ Hits       10266   10278   +12     
+ Misses      2977    2966   -11     
+ Partials     653     652    -1     

Impacted Files	Coverage Δ
...nternal/controllers/gateway/tcproute_controller.go	70.0% <0.0%> (-2.0%)	⬇️
internal/dataplane/parser/parser.go	89.6% <0.0%> (-1.7%)	⬇️
internal/dataplane/kongstate/service.go	66.0% <0.0%> (-1.3%)	⬇️
internal/controllers/gateway/gateway_utils.go	90.4% <0.0%> (+0.4%)	⬆️
internal/controllers/gateway/gateway_controller.go	67.9% <0.0%> (+1.1%)	⬆️
...ternal/controllers/gateway/httproute_controller.go	60.1% <0.0%> (+1.5%)	⬆️
...nternal/controllers/gateway/udproute_controller.go	71.6% <0.0%> (+2.1%)	⬆️
internal/util/builder/routenamespaces.go	71.4% <0.0%> (+21.4%)	⬆️
internal/util/builder/allowedroutes.go	100.0% <0.0%> (+50.0%)	⬆️

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