ci: build in release

[muzarski]

In hope to speed up the CI process.

Pre-review checklist

• I have split my patch into logically separate commits.
• All commit messages clearly explain what they change and why.
• PR description sums up the changes and reasons why they should be introduced.
• I have implemented Rust unit tests for the features/changes introduced.
• I have enabled appropriate tests in .github/workflows/build.yml in gtest_filter.
• I have enabled appropriate tests in .github/workflows/cassandra.yml in gtest_filter.

[muzarski]

I'm comparing with: #280

For Scylla ITs, we see significant improvement from 14-17 minutes to 9-12 minutes. Unfortunately, the slowest job (cassandra tests) is still slow... We see an improvement (21 minutes to 17 minutes), so we at least gain something. The cassandra tests are bounded by slow ccm cluster operations. Take for example: ConsistencyThreeNodeClusterTests.Integration_Cassandra_TwoNodesDecommissioned (146438 ms) - over 2 minutes for 1 test case !!!!!!!

I still think it is worth merging. We gain around 4 minutes per CI run.