Update default version to node20

[takost]

Make node20 default node version for runner internal operations. This can be opted-out by starting Runner with ACTIONS_RUNNER_FORCED_INTERNAL_NODE_VERSION=node16 or if DistributedTask.ForceInternalNodeVersionOnRunnerTo16 FF set to true (PR: https://github.com/github/actions-dotnet/pull/16155).

[ajschmidt8]

cross-posting the issue I created below for visibility:

• Composite Actions using Node 20 don't work with CentOS 7 #2906

The transition from Node 16 to Node 20 conflicts with the actions/runner claim of support for CentOS 7.

[jeremy-ke]

just in case anyone else runs into this issue running github agents on amazonlinux2 - github agent service startup mentioned a missing GLIBC_2.27/GLIBC_2.28 dependency for node20.

as mentioned in the pr description, setting export GITHUB_ACTIONS_RUNNER_FORCED_NODE_VERSION=node16 in the user data resolved this

[jonanderson10]

just in case anyone else runs into this issue running github agents on amazonlinux2 - github agent service startup mentioned a missing GLIBC_2.27/GLIBC_2.28 dependency for node20.

as mentioned in the pr description, setting export GITHUB_ACTIONS_RUNNER_FORCED_NODE_VERSION=node16 in the user data resolved this

I just ran into this as well, thanks!