Clean up ARM toolchains from get_mbed_official_release()

[bridadan]

Previously it would return ARM for ARMC5, which was quite confusing, since supplying -t ARM will select either ARMC5 or ARMC6 internally. Now it will return ARMC5 if the targets only supports ARMC5, ARMC5 and ARMC6 if it supports both, or just ARMC6 if it only supports ARMC6.

Description

Pull request type

[ ] Fix
[x] Refactor
[ ] Target update
[ ] Functionality change
[ ] Docs update
[ ] Test update
[ ] Breaking change

Reviewers

@OPpuolitaival - I'd like to double check with you that this won't cause issues or break assumptions in the CI

Release Notes

[ciarmcom]

@bridadan, thank you for your changes.
@OPpuolitaival @ARMmbed/mbed-os-tools @ARMmbed/mbed-os-maintainers please review.

[OPpuolitaival]

Looks great!

[0xc0170]

@OPpuolitaival - I'd like to double check with you that this won't cause issues or break assumptions in the CI

As this is refactor, will go into 5.13 (let us know if this is not the case)

[0xc0170]

CI started

[mbed-ci]

Test run: FAILED

Summary: 4 of 7 test jobs failed
Build number : 1
Build artifacts

Failed test jobs:

• jenkins-ci/mbed-os-ci_build-IAR
• jenkins-ci/mbed-os-ci_mbed2-build-IAR
• jenkins-ci/mbed-os-ci_mbed2-build-GCC_ARM
• jenkins-ci/mbed-os-ci_build-GCC_ARM

[alekla01]

restarted CI

[alekla01]

This pr in its current form does break the current assumptions in the CI, which is why no targets were built with ARM toolchains.

[0xc0170]

This pr in its current form does break the current assumptions in the CI, which is why no targets were built with ARM toolchains.

Will wait for CI update

[mbed-ci]

Test run: FAILED

Summary: 2 of 11 test jobs failed
Build number : 2
Build artifacts

Failed test jobs:

• jenkins-ci/mbed-os-ci_dynamic-memory-usage
• jenkins-ci/mbed-os-ci_greentea-test

[alekla01]

CI updated.

[0xc0170]

CI restarted (rebuild)

[mbed-ci]

Test run: FAILED

Summary: 1 of 11 test jobs failed
Build number : 3
Build artifacts

Failed test jobs:

• jenkins-ci/mbed-os-ci_dynamic-memory-usage

[alekla01]

restarted jenkins-ci/mbed-os-ci_dynamic-memory-usage

[adbridge]

ci started

[mbed-ci]

Test run: FAILED

Summary: 1 of 11 test jobs failed
Build number : 5
Build artifacts

Failed test jobs:

• jenkins-ci/mbed-os-ci_exporter

[adbridge]

@bridadan please take a look at the test failures

[bridadan]

@adbridge looks like some uvision6 jobs timed out. Does that mean it needs to be restarted?

[adbridge]

ci restarted

[mbed-ci]

Test run: FAILED

Summary: 1 of 11 test jobs failed
Build number : 6
Build artifacts

Failed test jobs:

• jenkins-ci/mbed-os-ci_cloud-client-test

[alekla01]

Restarted cloud-client-test