WIP: Upgrade to google.golang.org/grpc v1.66.2

[aknuds1]

What this PR does

Upgrade google.golang.org/grpc from v1.65.0 to v1.66.2. The performance regression referenced from dskit's reversal to v1.65.0 is fixed in v1.66.2, and the potential functional regression also referenced in said reversal is Loki specific.

What we found out is that v1.66 fixes a serious performance bottleneck in conjunction with compression; the decompress function is optimized through memory pooling, whereas v1.65.0 would use io.ReadAll and cause a lot of allocations during decompression. As a result, we saw ingester CPU usage increase by ~40% when enabling gRPC compression. The increase is now much more modest, maybe ~7% based on observations.

Also upgrade github.com/googleapis/enterprise-certificate-proxy to v0.3.4, to fix a checksum issue in v0.3.3 (v0.3.4 was released to take care of this). With v0.3.3, building on OS X fails:

✗ go mod tidy && go mod vendor
go: downloading github.com/googleapis/enterprise-certificate-proxy v0.3.3
verifying github.com/googleapis/[email protected]: checksum mismatch
	downloaded: h1:G6q7VHBoU74wQHXFsZSLMPl0rFw0ZDrlZ3rt6/aTBII=
	go.sum:     h1:QRje2j5GZimBzlbhGA2V2QlGNgL8G6e+wGo/+/2bWI0=

SECURITY ERROR
This download does NOT match an earlier download recorded in go.sum.
The bits may have been replaced on the origin server, or an attacker may
have intercepted the download attempt.

Which issue(s) this PR fixes or relates to

Checklist

• Tests updated.
• Documentation added.
• CHANGELOG.md updated - the order of entries should be [CHANGE], [FEATURE], [ENHANCEMENT], [BUGFIX].
• about-versioning.md updated with experimental features.

[aknuds1]

Some tests are breaking for this upgrade, have to fix them.

[aknuds1]

Tests currently pass, but that is through undoing some memory unsafe optimizations in the mimirpb package. We want to investigate whether the optimizations can safely be retained.