Revendor gardener/gardener@v1.38 and update Golang version to 1.17

[rfranzke]

How to categorize this PR?

/area open-source
/kind enhancement
/platform azure

What this PR does / why we need it:
Revendor gardener/gardener@v1.38 and update Golang version to 1.17.

ℹ️ The branch.cfg definition is still using Golang 1.16, hence, the verify step fails. Once this PR is approved, we can adapt the branch.cfg (also update to 1.17) and then re-trigger the CI pipeline for this PR.

Which issue(s) this PR fixes:
Part of gardener/gardener#4866

Release note:

The Golang version has been updated to `1.17.5`.

Since go1.17 both `net.ParseIP` and `net.ParseCIDR` reject leading zeros in the dot-decimal notation of IPv4 addresses. With the update to go1.17, admission-azure now rejects Shoot objects with CIDR ranges that have such leading zeros in the dot-decimal notation. Before updating to this version of admission-azure, make sure that there are no Shoot objects with leading zeros in the dot-decimal notation of an IPv4 address. For reference: https://nvd.nist.gov/vuln/detail/CVE-2021-29923

[rfranzke]

/test

[testmachinery]

Testrun: e2e-s92mm
Workflow: e2e-s92mm-wf
Phase: Succeeded

+---------------------+---------------------+-----------+----------+
|        NAME         |        STEP         |   PHASE   | DURATION |
+---------------------+---------------------+-----------+----------+
| infrastructure-test | infrastructure-test | Succeeded | 25m35s   |
+---------------------+---------------------+-----------+----------+

[rfranzke]

/ready
/invite @dkistner @kon-angelo @stoyanr

[ialidzhikov]

/lgtm
/squash

[dkistner]

/lgtm

[kon-angelo]

/lgtm