Waitable should check callback_group if it can be executed. (backport #1001)

[mergify]

This is an automatic backport of pull request #1001 done by Mergify.
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[fujitatomoya]

CI:

• Linux
• Linux-aarch64
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[fujitatomoya]

CI:

• Windows

[fujitatomoya]

https://ci.ros2.org/job/ci_windows/18026/ are unrelated to this fix, i will go ahead to merge this.