Fix dependencies and adjust runners type

Install OpenSSL since tester3 is enforced.

New runners do not seem to come with openssl or cmake pre-installed.

Also,
- fix comparison for uarch specific configurations
- fix artifacts name for build native.
- use SVE enabled instances (c7g)
- use larger (x->2x) instances so tests run slightly faster without
  compromising on availability.

.github/workflows/build_and_test.yml

@@ -33,6 +33,8 @@ jobs:
     # - Arm-hosted (via AWS), only Linux c6g or c7g.
     #   Please refer to the documentation at
     #   https://gitlab.arm.com/tooling/gha-runner-docs
+    #   Here we use c7g (2xlarge) for easy access to
+    #   SVE-enabled runners (with 8 vCPUs).
     runs-on: ${{ matrix.os }}
     strategy:
       fail-fast: false