ci: Fix remote caching

[lukedirtwalker]

It seems that if --disk-cache with a valid location is present, bazel will ignore --remote-cache.
Thus we must override --disk-cache to the empty value in the .bazelrc_ci file,
so that on the CI only the remote cache is used.

Also switch to using the bazel cache via grpc.

The problem was introduced by #3591

This change is 

[karampok]

Reviewable status: 0 of 2 files reviewed, 1 unresolved discussion (waiting on @karampok and @lukedirtwalker)

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.bazelrc_ci, line 1 at r1 (raw file):

build --disk_cache= --remote_cache=grpc://localhost:9092

I would like a link to the documentation
or maybe
build --disc_cash=this/has/to/invalid/so/remote/cache/to/work :)

otherwise someone will just see this as a mistake and silently fix it

[lukedirtwalker]

Reviewable status: 0 of 2 files reviewed, 1 unresolved discussion (waiting on @karampok)

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.bazelrc_ci, line 1 at r1 (raw file):

Previously, karampok (Konstantinos) wrote…

I would like a link to the documentation
or maybe
build --disc_cash=this/has/to/invalid/so/remote/cache/to/work :)

otherwise someone will just see this as a mistake and silently fix it

Done.

[karampok]

Reviewed 1 of 2 files at r1, 1 of 1 files at r2.
Reviewable status: complete! all files reviewed, all discussions resolved

[karampok]

Reviewable status: complete! all files reviewed, all discussions resolved

[karampok]

Reviewed 1 of 1 files at r3.
Reviewable status: complete! all files reviewed, all discussions resolved

[karampok]

Reviewable status: complete! all files reviewed, all discussions resolved

[karampok]

Reviewed 1 of 1 files at r4.
Reviewable status: complete! all files reviewed, all discussions resolved