OpenSearch performance benchmark dashboard improvements.

[rishabh6788]

Below is the feedback we have received from active dashboard users.

• Having both workloads on the same dashboard is confusing, there is point to have them together, since we are not going to compare them. On the other hand, may be having SegRep enabled vs disabled on the same dashboard is make sense to compare them
• Legends are not clear. For example “2.9.0 - false - x64” : What false means? we already put x64 on the dashboard title.
• Instead of having minor versions on different lines, I would like to see one line represent the current 2.x version, and may be add tags when minor release happened.
• Is there any mechanism to set alarms when specific metric reaches a threshold. For example: if indexing throughput dropped by x%, then send an Alarm.
• Is there any way for engineers to add new monitoring dashboard for example by submitting a PR, instead of creating a github issue and wait EE team to do it.
• May be having different tab per processor arm64 vs x64 will make it more easier

[Divyaasm]

@rishabh6788 will further add the acceptance criteria