re-enable CGO and buildmode pie

[pchila]

What is the problem this PR solves?

Re-enable CGO and buildmode pie to restore fleet-server metrics on darwin

How does this PR solve the problem?

How to test this PR locally

Design Checklist

• I have ensured my design is stateless and will work when multiple fleet-server instances are behind a load balancer.
• I have or intend to scale test my changes, ensuring it will work reliably with 100K+ agents connected.
• I have included fail safe mechanisms to limit the load on fleet-server: rate limiting, circuit breakers, caching, load shedding, etc.

Checklist

• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have made corresponding change to the default configuration files
• I have added tests that prove my fix is effective or that my feature works
• I have added an entry in ./changelog/fragments using the changelog tool

Related issues

[prodsecmachine]

✅ Snyk checks have passed. No issues have been found so far.

Status	Scanner	Critical	High	Medium	Low	Total (0)
✅	Licenses	0	0	0	0	0 issues
✅	Open Source Security	0	0	0	0	0 issues

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[mergify]

This pull request does not have a backport label. Could you fix it @pchila? 🙏
To fixup this pull request, you need to add the backport labels for the needed
branches, such as:

• backport-./d./d is the label to automatically backport to the 8./d branch. /d is the digit
• backport-active-all is the label that automatically backports to all active branches.
• backport-active-8 is the label that automatically backports to all active minor branches for the 8 major.
• backport-active-9 is the label that automatically backports to all active minor branches for the 9 major.

[rubenruizdegauna]

LGTM

[pkoutsovasilis]

LGTM, checked the produced artifacts and the GLIBC dependencies are compatible with our OS matrix support

fleet-server-9.3.0-linux-x86_64/fleet-server
GLIBC_2.3.2
GLIBC_2.2.5
GLIBC_2.2.5

fleet-server-9.3.0-linux-arm64/fleet-server
GLIBC_2.17
GLIBC_2.17

[github-actions]

@Mergifyio backport 8.19 9.0 9.1 9.2

[mergify]

backport 8.19 9.0 9.1 9.2

✅ Backports have been created

• #5718 [8.19](backport #5715) re-enable CGO and buildmode pie has been created for branch 8.19
• #5719 [9.0](backport #5715) re-enable CGO and buildmode pie has been created for branch 9.0 but encountered conflicts
• #5720 [9.1](backport #5715) re-enable CGO and buildmode pie has been created for branch 9.1
• #5721 [9.2](backport #5715) re-enable CGO and buildmode pie has been created for branch 9.2