FDN-4261: switch to Shenandoah GC

[nicolagi]

Summary

• Switch JVM garbage collector from G1GC to ShenandoahGC for lower pause times (dependency-api and dependency-www)
• Bump generic-charts to v2.0.10 which supports the garbageCollector knob

Test plan

• Verify ArgoCD diff shows ShenandoahGC in JAVA_OPTS for both services
• Monitor GC pause times after deploy

🤖 Generated with Claude Code

[flow-tech]

Argo diff output for dependency-www:

===== /Service production/dependency-www ======
11c11
<     helm.sh/chart: flow-generic-1.6.59
---
>     helm.sh/chart: flow-generic-1.6.60

===== apps/Deployment production/dependency-www-live ======
16c16
<     helm.sh/chart: flow-generic-1.6.59
---
>     helm.sh/chart: flow-generic-1.6.60
552,553c552,554
<           value: -Xms2100m -Xmx2100m -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=/dumps/oom.bin
<             -XX:+UseG1GC -XX:+UseStringDeduplication -XX:FlightRecorderOptions=stackdepth=256
---
>           value: -Xms2100m -Xmx2100m -XX:+UseShenandoahGC -XX:+HeapDumpOnOutOfMemoryError
>             -XX:HeapDumpPath=/dumps/oom.bin -XX:+UseStringDeduplication -XX:FlightRecorderOptions=stackdepth=256
>             -Xlog:gc*:stdout:time,uptime,level,tags

===== datadoghq.com/DatadogMonitor datadog/dependency-www-errorrate ======
145d144
<   - generated:kubernetes

===== networking.istio.io/Gateway production/dependency-www-flow-io ======
17c17
<     helm.sh/chart: flow-generic-1.6.59
---
>     helm.sh/chart: flow-generic-1.6.60

===== networking.istio.io/VirtualService production/dependency-www-live ======
12c12
<     helm.sh/chart: flow-generic-1.6.59
---
>     helm.sh/chart: flow-generic-1.6.60

[flow-tech]

Argo diff output for dependency-api:

===== /Service production/dependency ======
11c11
<     helm.sh/chart: flow-generic-1.6.59
---
>     helm.sh/chart: flow-generic-1.6.60

===== apps/Deployment production/dependency-api-live ======
16c16
<     helm.sh/chart: flow-generic-1.6.59
---
>     helm.sh/chart: flow-generic-1.6.60
552,553c552,554
<           value: -Xms2100m -Xmx2100m -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=/dumps/oom.bin
<             -XX:+UseG1GC -XX:+UseStringDeduplication -XX:FlightRecorderOptions=stackdepth=256
---
>           value: -Xms2100m -Xmx2100m -XX:+UseShenandoahGC -XX:+HeapDumpOnOutOfMemoryError
>             -XX:HeapDumpPath=/dumps/oom.bin -XX:+UseStringDeduplication -XX:FlightRecorderOptions=stackdepth=256
>             -Xlog:gc*:stdout:time,uptime,level,tags

===== datadoghq.com/DatadogMonitor datadog/dependency-api-errorrate ======
145d144
<   - generated:kubernetes

===== networking.istio.io/Gateway production/dependency-flow-io ======
17c17
<     helm.sh/chart: flow-generic-1.6.59
---
>     helm.sh/chart: flow-generic-1.6.60

===== networking.istio.io/VirtualService production/dependency-api-live ======
12c12
<     helm.sh/chart: flow-generic-1.6.59
---
>     helm.sh/chart: flow-generic-1.6.60