Reintroduce UPGRADE_NO_OP (#8113)

[acohen4]

env-var to ease 'helm upgrade' auto-restarting pods to consume new secrets. This is a stop gap until we migrate secrets to volumes, and watch their inodes to restart (#8113)

[codecov]

Codecov Report

Merging #8118 (5767450) into 2.3.x (6b423ae) will decrease coverage by 18.83%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##            2.3.x   #8118       +/-   ##
==========================================
- Coverage   22.28%   3.45%   -18.84%     
==========================================
  Files         415     201      -214     
  Lines      112171   74136    -38035     
==========================================
- Hits        24995    2559    -22436     
+ Misses      82900   71216    -11684     
+ Partials     4276     361     -3915     

Impacted Files	Coverage Δ
src/server/auth/db.go	0.00% <0.00%> (-100.00%)	⬇️
src/internal/watch/op.go	0.00% <0.00%> (-100.00%)	⬇️
src/internal/miscutil/log.go	0.00% <0.00%> (-100.00%)	⬇️
src/internal/miscutil/math.go	0.00% <0.00%> (-100.00%)	⬇️
src/internal/grpcutil/error.go	0.00% <0.00%> (-100.00%)	⬇️
src/internal/randutil/unique.go	0.00% <0.00%> (-100.00%)	⬇️
src/internal/testutil/naming.go	0.00% <0.00%> (-100.00%)	⬇️
src/internal/storage/fileset/metadata_store.go	0.00% <0.00%> (-100.00%)	⬇️
src/internal/storage/track/tracker.go	3.70% <0.00%> (-96.30%)	⬇️
src/internal/task/etcd_queue.go	0.00% <0.00%> (-93.55%)	⬇️
... and 362 more

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