fix(prometheus): PrometheusMeterRegistry to support same name with different set of tag keys

[christosarvanitis]

Fixes: #26
Additionally the micrometer libraries are updated to the available LTS.

The work done in this PR is duplicated/imported from micrometer-metrics/micrometer#2653 that attempts to fix the limitation on the micrometer-prometheus library.

Loading in a local environment and triggering some pipelines the Orca metrics show that the issue is fixed:

# HELP stage_invocations_duration_total  
# TYPE stage_invocations_duration_total counter
stage_invocations_duration_total{armSpinSvcVer="2.27.0-snapshot.20210708112241.6b80ae6",lib="aop",libVer="v1.1.2-SNAPSHOT",ossSpinSvcVer="2.20.0-20210422230020",percentile="T008C",spinSvc="orca",spinnakerRelease="1.26.2",stageType="manualJudgment",statistic="percentile",status="SUCCEEDED",version="2.20.0-20210422230020",} 1.0
stage_invocations_duration_total{armSpinSvcVer="2.27.0-snapshot.20210708112241.6b80ae6",lib="aop",libVer="v1.1.2-SNAPSHOT",ossSpinSvcVer="2.20.0-20210422230020",percentile="T007C",spinSvc="orca",spinnakerRelease="1.26.2",stageType="savePipeline",statistic="percentile",status="SUCCEEDED",version="2.20.0-20210422230020",} 1.0
stage_invocations_duration_total{armSpinSvcVer="2.27.0-snapshot.20210708112241.6b80ae6",lib="aop",libVer="v1.1.2-SNAPSHOT",ossSpinSvcVer="2.20.0-20210422230020",percentile="T008E",spinSvc="orca",spinnakerRelease="1.26.2",stageType="wait",statistic="percentile",status="SUCCEEDED",version="2.20.0-20210422230020",} 1.0
stage_invocations_duration_total{armSpinSvcVer="2.27.0-snapshot.20210708112241.6b80ae6",lib="aop",libVer="v1.1.2-SNAPSHOT",ossSpinSvcVer="2.20.0-20210422230020",percentile="T0084",spinSvc="orca",spinnakerRelease="1.26.2",stageType="wait",statistic="percentile",status="SUCCEEDED",version="2.20.0-20210422230020",} 1.0
stage_invocations_duration_total{armSpinSvcVer="2.27.0-snapshot.20210708112241.6b80ae6",lib="aop",libVer="v1.1.2-SNAPSHOT",ossSpinSvcVer="2.20.0-20210422230020",percentile="T0098",spinSvc="orca",spinnakerRelease="1.26.2",stageType="wait",statistic="percentile",status="SUCCEEDED",version="2.20.0-20210422230020",} 1.0
stage_invocations_duration_total{armSpinSvcVer="2.27.0-snapshot.20210708112241.6b80ae6",lib="aop",libVer="v1.1.2-SNAPSHOT",ossSpinSvcVer="2.20.0-20210422230020",percentile="T0096",spinSvc="orca",spinnakerRelease="1.26.2",stageType="wait",statistic="percentile",status="SUCCEEDED",version="2.20.0-20210422230020",} 1.0
stage_invocations_duration_total{armSpinSvcVer="2.27.0-snapshot.20210708112241.6b80ae6",lib="aop",libVer="v1.1.2-SNAPSHOT",ossSpinSvcVer="2.20.0-20210422230020",percentile="T008D",spinSvc="orca",spinnakerRelease="1.26.2",stageType="manualJudgment",statistic="percentile",status="SUCCEEDED",version="2.20.0-20210422230020",} 1.0
stage_invocations_duration_total{armSpinSvcVer="2.27.0-snapshot.20210708112241.6b80ae6",lib="aop",libVer="v1.1.2-SNAPSHOT",ossSpinSvcVer="2.20.0-20210422230020",percentile="T0083",spinSvc="orca",spinnakerRelease="1.26.2",stageType="savePipeline",statistic="percentile",status="SUCCEEDED",version="2.20.0-20210422230020",} 1.0
stage_invocations_duration_total{armSpinSvcVer="2.27.0-snapshot.20210708112241.6b80ae6",lib="aop",libVer="v1.1.2-SNAPSHOT",ossSpinSvcVer="2.20.0-20210422230020",percentile="T007E",spinSvc="orca",spinnakerRelease="1.26.2",stageType="savePipeline",statistic="percentile",status="SUCCEEDED",version="2.20.0-20210422230020",} 1.0
 % curl -s 127.0.0.1:8083/aop-prometheus | grep stage_invocations_duration_total | sort | wc -l 
      11
 % curl -s 127.0.0.1:8083/aop-prometheus | grep stage_invocations_duration_total | sort |uniq|  wc -l 
      11

[coveralls]

Pull Request Test Coverage Report for Build #73

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage remained the same at 93.309%

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Files with Coverage Reduction	New Missed Lines	%
file:/home/runner/work/armory-observability-plugin/armory-observability-plugin/common/src/main/java/io/armory/plugin/observability/newrelic/NewRelicRegistrySupplier.java	1	95.0%

Totals
Change from base Build #71:	0.0%
Covered Lines:	251
Relevant Lines:	269

---

💛 - Coveralls