PHOENIX-7729: Identify top N slowest parallel scans for metrics reporting

[sanjeet006py]

JIRA: PHOENIX-7729

• The change captures the metrics for top N slowest scans. The feature is controlled by two configs: phoenix.slowest.scan.metrics.count and phoenix.scan.metrics.by.region.enabled.
• phoenix.slowest.scan.metrics.count specifies the value of N for capturing metrics for top N slowest scan metrics. The value should be > 0 to enable capturing top N slowest scan metrics.
• phoenix.scan.metrics.by.region.enabled specifies whether to capture region hash and RS name along with HBase scan metrics.
• Example of top N slowest scan metrics for N = 2:

[[{"table":"N000001","regions":[{"region":"e43c8b60c4cddf2acc0417d10ebbac24","server":"hbase.regionsserver.hostname1,52433,1763102072284","rsp":27,"rg":1,"rr":0,"brfc":0,"brfm":0,"ws":1,"rp":1,"broc":1,"rsqw":0,"brff":134,"rs":56,"frt":4,"n":28,"rrs":0,"wf":0,"rpr":0,"nsr":0,"rrr":0}]}],[{"table":"N000001","regions":[{"region":"9d77823d1e703b6c6d098006014f7a74","server":"hbase.regionsserver.hostname1,52433,1763102072284","rsp":27,"rg":1,"rr":0,"brfc":0,"brfm":0,"ws":1,"rp":1,"broc":1,"rsqw":0,"brff":128,"rs":50,"frt":4,"n":28,"rrs":0,"wf":0,"rpr":0,"nsr":0,"rrr":0}]}]]

• For a query having subqueries or JOINs, we need to identify scans in query and subquery which together take most time. And, we need to find such top N list of scans for the given value of N. This PR also handles the aforementioned specified case. For example output, please refer to: SlowestScanMetricsIT.

[sanjeet006py]

Revert all the changes in this file before merge.