sidecar: Use injectLabels optimizations

[bwplotka]

AC:

• Use the same optimization as here but in the sidecar.

The nontrivial thing is to parse the map in an ordered fashion so labels are sorted:

thanos/pkg/store/prometheus.go

Line 163 in 4b89eea

lset := make([]labelpb.ZLabel, 0, len(lbm)+len(externalLabels))

[Biswajitghosh98]

Hi @bwplotka!
I was looking forward to be a part of Thanos, and I'd like to start with this issue

[stale]

Hello 👋 Looks like there was no activity on this issue for the last two months.
Do you mind updating us on the status? Is this still reproducible or needed? If yes, just comment on this PR or push a commit. Thanks! 🤗
If there will be no activity in the next two weeks, this issue will be closed (we can always reopen an issue if we need!). Alternatively, use remind command if you wish to be reminded at some point in future.

[kakkoyun]

Still valid.

[longngn]

@bwplotka I'm looking into this issue. However, I stumbles across some problems:

1. Does Prometheus /api/v1/series API guarantee to return sorted labels?
2. Even if the API returns sorted labels, JSON spec and encoding/json package don't guarantee object ordering (see more: encoding/json: no way to preserve the order of map keys golang/go#27179)

[stale]

Hello 👋 Looks like there was no activity on this issue for the last two months.
Do you mind updating us on the status? Is this still reproducible or needed? If yes, just comment on this PR or push a commit. Thanks! 🤗
If there will be no activity in the next two weeks, this issue will be closed (we can always reopen an issue if we need!). Alternatively, use remind command if you wish to be reminded at some point in future.

[stale]

Closing for now as promised, let us know if you need this to be reopened! 🤗

[stale]

Hello 👋 Looks like there was no activity on this issue for the last two months.
Do you mind updating us on the status? Is this still reproducible or needed? If yes, just comment on this PR or push a commit. Thanks! 🤗
If there will be no activity in the next two weeks, this issue will be closed (we can always reopen an issue if we need!). Alternatively, use remind command if you wish to be reminded at some point in future.

[stale]

Closing for now as promised, let us know if you need this to be reopened! 🤗