[-] migrate all panels in Health Check dashboard to table format

[0xgouda]

1. Remove $online_interval variable.
   • There is no reason for having a new time variable in addition to Grafana's time range.
2. Migrate all panels to table format.
   • panels had 3 approaches to add the time column required by time series format:
     1. select 0 as time, ....
        • not necessary, remove 0 as time and use table format instead.
     2. select time, .....
        • same as above.
     3. select $__timeGroup(time, $online_interval) .... group by 1.
        • not necessary as the data is already filtered by the user-specified time range using $__timeFilter(time), so any further time grouping is not required, but actually can make the result imprecise, as some data that should be shown might fall into a different group that will be ignored.
3. Remove where time > now() - '$online_interval'::interval and use $__timeFilter(time) instead.

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TODO:

• extra check on changed SQL queries to ensure I didn't break anything.

[coveralls]

Pull Request Test Coverage Report for Build 19893173791

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 73.615%

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Totals
Change from base Build 19889697687:	0.0%
Covered Lines:	3694
Relevant Lines:	5018

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💛 - Coveralls

[pashagolub]

Perfect! 👍

[pashagolub]

Please, resolve conflicts. Then squash and merge. Thanks!