Upgrade to Bazel 5.1 in Provisioned

[jwnimmer-tri]

https://github.com/bazelbuild/bazel/releases/tag/5.1.0

Prior issue: #16447.
Prior PR: #16523.

No hurry on this, it's OK for this to wait until the 2022-04-01 externals upgrade / bionic drop time period. I'll be running it locally in the meantime and will chime in about any local problems I see.

[BetsyMcPhail]

Note that Homebrew is still at 5.0.0

[BetsyMcPhail]

• Upgrade recommended Bazel version to 5.1.0 for Linux - setup: Upgrade recommended Bazel version to 5.1.0 for Linux #16878
• Update Linux provisioned images - Coordinate with update with [workspace] install flask for unit tests #16864
• Upgrade recommended Bazel version to 5.1.1 for Mac setup: Upgrade recommended Bazel version to 5.0 #16523
• Update Mac provisioned images

[mwoehlke-kitware]

...wheels? (macOS wheel will follow homebrew / CI provisioning, but the Linux wheels need to be updated.)

FYI, I'm running a local wheel build with 5.1.0 now... probably going to take a few hours since this invalidated all of the caching. (Would there be any value in moving Bazel provisioning to after dependencies but before Python provisioning?)

[BetsyMcPhail]

@mwoehlke-kitware tools/wheel/image/provision-base.sh was updated as part of the Linux PR. Where else do I need to update? I probably missed it last time as well so we may be 2 versions out of date.

[mwoehlke-kitware]

Ah, apparently my local checkout is that far out of date 😢 .

[BetsyMcPhail]

Homebrew was updated to 5.1.1 on 4/8. The nightly and weekly unprovisioned jobs ran with the updated version over the weekend.