Deps: Bump Go version in Dockerfiles and test/kokoro/xds.sh

[arjan-bal]

Since the minimum supported Go version was bumped in #7624, the Docker build for the psm interop client and server has been failing with the following error:

#10 [build 4/4] RUN cd interop/xds/client && go build -tags osusergo,netgo .
#10 0.248 go: ../go.mod requires go >= 1.22.7 (running go 1.21.13; GOTOOLCHAIN=local)
#10 ERROR: process "/bin/sh -c cd interop/xds/client && go build -tags osusergo,netgo ." did not complete successfully: exit code: 1
------
 > [build 4/4] RUN cd interop/xds/client && go build -tags osusergo,netgo .:
0.248 go: ../go.mod requires go >= 1.22.7 (running go 1.21.13; GOTOOLCHAIN=local)
------

Verified that the docker build succeeds with the change in base image version to 1.22.

 docker build -f examples/features/csm_observability/client/Dockerfile . && \
 docker build -f examples/features/csm_observability/server/Dockerfile . && \
 docker build -f  interop/observability/Dockerfile . && \
 docker build -f  interop/xds/client/Dockerfile . && \
 docker build -f  interop/xds/server/Dockerfile . 

Verified that the download URL still works in xds.sh.

gofilename=go1.23.0.linux-amd64.tar.gz
curl --retry 3 -O -L "https://go.dev/dl/${gofilename}"

RELEASE NOTES: N/A

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.76%. Comparing base (393fbc3) to head (4b60428).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #7629      +/-   ##
==========================================
- Coverage   81.86%   81.76%   -0.11%     
==========================================
  Files         361      361              
  Lines       27817    27817              
==========================================
- Hits        22773    22745      -28     
- Misses       3849     3867      +18     
- Partials     1195     1205      +10     

see 24 files with indirect coverage changes

[dfawley]

Go 1.23 is out now -- should we go straight to that version instead?

[arjan-bal]

Updated to go1.23. Also changed remaining Dockerfiles in the repo and test/kokoro/xds.sh to use go1.23.

[dfawley]

👍 Then we won't need to update again in 6 months.

[dfawley]

👍 Then we won't need to update again in 6 months.