Add overrides configmap to querier, update docs for new limit

[annanay25]

Signed-off-by: Annanay annanayagarwal@gmail.com

What this PR does:

• [Jsonnet] Add overrides confimap to the querier
• [Docs] Add docs for the new limit and revamp the overrides section a bit
• Splits CI runners for unit and integration tests
• Optimised integration tests a little

Before:

--- PASS: TestCompression (17.20s)
--- PASS: TestAllInOne (91.78s)
    --- PASS: TestAllInOne/s3 (31.36s)
    --- PASS: TestAllInOne/azure (35.26s)
    --- PASS: TestAllInOne/gcs (25.16s)
--- PASS: TestMicroservices (122.80s)
--- PASS: TestScalableSingleBinary (152.11s)
--- PASS: TestLimits (17.05s)

After

--- PASS: TestCompression (17.63s)
--- PASS: TestAllInOne (77.20s)
    --- PASS: TestAllInOne/s3 (24.66s)
    --- PASS: TestAllInOne/azure (28.47s)
    --- PASS: TestAllInOne/gcs (24.07s)
--- PASS: TestMicroservices (66.50s)
--- PASS: TestScalableSingleBinary (65.11s)
--- PASS: TestLimits (16.73s)

Ok, the machine used in second run might have been better but still reductions in TestMicroservices and TestScalableSingleBinary.

Which issue(s) this PR fixes:
Follow up from #1068

Marking draft because this is 100% going to collide with #1129

Checklist

• NA Tests updated
• Documentation added
• NA CHANGELOG.md updated - the order of entries should be [CHANGE], [FEATURE], [ENHANCEMENT], [BUGFIX]

[mapno]

LGTM

[annanay25]

@KMiller-Grafana Thanks for the review. I'm going to merge this one as I have addressed your comments. There were no other docs changes.

Edit: Oh I can't merge until you approve. I'll wait :)

[KMiller-Grafana]

Docs look good to me now. Thanks for the changes.