[Backport 7.69.x] Fix deps builds

[datadog-agent-integrations-bot]

Backport 0e34600 from #21019.

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What does this PR do?

It fixes two issues with dependency builds: kerberos.org being down and a failure to build zlib on windows (via vcpkg), by:

• Changing mirror for krb5 to a working source.
• Pinning vs studio bootstrapper to a past version (taken from https://learn.microsoft.com/en-us/visualstudio/releases/2022/release-history#fixed-version-bootstrappers). This is what ended up fixing the Windows build.
• It also goes back to pinning vcpkg. This ended up not being the culprit this time, but it could cause issues in the future, and the convenience of not having to update the reference in some dep updates is not enough to justify the risk of something breaking.

Motivation

Failures while trying to update curl (#20998), which were unrelated to the update:

• Kerberos.org being down: https://github.com/DataDog/integrations-core/actions/runs/16883316720/job/47880218094?pr=20998#step:10:13233
• Failure to build zlib on windows: https://github.com/DataDog/integrations-core/actions/runs/16883316720/job/47880218097?pr=20998#step:10:628

Review checklist (to be filled by reviewers)

• Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• Add the qa/skip-qa label if the PR doesn't need to be tested during QA.
• If you need to backport this PR to another branch, you can add the backport/<branch-name> label to the PR and it will automatically open a backport PR once this one is merged