[2.0.x] Retries and Contract Builders for Tags

[scottarnette]

Change Description

Added ability to retry test steps, even if they have passed.

• Unit tests, WASM spec tests, serial tests, and long running tests can be manually retried as many times as desired.
• If a build is more than a few days old, there could be issues with the test steps acquiring the build artifact.

Fixed issue where Contract Builder step did not run on Github tags.

• Originally only created for release, master, and develop branches. This now automatically builds for new tags moving forward.
• Still able to force a Contract Builder image via the FORCE_BINARIES_BUILD flag.

See:
https://buildkite.com/EOSIO/eosio/builds/19294#15066bf2-8f21-4d74-96ba-982b949918c3 | 3 runs of a single test that all pass.

Consensus Changes

• Consensus Changes

API Changes

• API Changes

Documentation Additions

• Documentation Additions