release-23.2: server: fix total latency time on sql stats call

[blathers-crl]

Backport 1/1 commits from #116976 on behalf of @maryliag.

/cc @cockroachdb/release

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For the top activity tables, we have a column execution_total_cluster_seconds with the total latency of all executions of that period. This value is important because the top activity table have up to 500 rows per aggregated timestamp, so if we add all latencies from it, we won't have the total, only the total of the top. We then have a column that has that total of that hour which is based on the main table.
Previously, when making a request to the top activity table we were returning only of of those values as the total, which works as expected if your select is in a single aggregation period. The majority of requests won't be this way, so we need to add the values from all aggregated period selects.

This commit update the query for the total select to get one value from each aggregated_ts and then adding those.

Part Of CRDB-34884

Release note (bug fix): Fix value used for the total runtime on sql stats, which was using the wrong value previously, causing the UI to display values with more than 100%.

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Release justification: bug fix

[blathers-crl]

Thanks for opening a backport.

Please check the backport criteria before merging:

• Backports should only be created for serious
  issues or test-only changes.
• Backports should not break backwards-compatibility.
• Backports should change as little code as possible.
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• Backports should not add new functionality (except as defined
  here).
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  TL. For more information as to how that review should be conducted, please consult the backport
  policy.

If your backport adds new functionality, please ensure that the following additional criteria are satisfied:

• There is a high priority need for the functionality that cannot wait until the next release and is difficult to address in another way.
• The new functionality is additive-only and only runs for clusters which have specifically “opted in” to it (e.g. by a cluster setting).
• New code is protected by a conditional check that is trivial to verify and ensures that it only runs for opt-in clusters. State changes must be further protected such that nodes running old binaries will not be negatively impacted by the new state (with a mixed version test added).
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  channel (#db-backports-point-releases or #db-backports-XX-X-release) for awareness and discussion.

Also, please add a brief release justification to the body of your PR to justify this
backport.

[cockroach-teamcity]

This change is 

[mgartner]

Reviewed 1 of 2 files at r1, all commit messages.
Reviewable status: complete! 0 of 0 LGTMs obtained (waiting on @abarganier, @blathers-crl[bot], @maryliag, @petermattis, and @xinhaoz)

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-- commits line 12 at r1:
nit: "of of" => "one of" (I think?)