multiple: switch to math/rand/v2

[marcoferrer]

Fixes #7293

This PR replaces usage of math/rand with math/rand/v2.

RELEASE NOTES: none

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.80%. Comparing base (6fd86d3) to head (9119f36).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #7711      +/-   ##
==========================================
- Coverage   81.84%   81.80%   -0.04%     
==========================================
  Files         374      374              
  Lines       38151    38149       -2     
==========================================
- Hits        31224    31208      -16     
- Misses       5663     5672       +9     
- Partials     1264     1269       +5     

Files with missing lines	Coverage Δ
balancer/endpointsharding/endpointsharding.go	64.86% <100.00%> (ø)
balancer/grpclb/grpclb_picker.go	96.70% <100.00%> (ø)
balancer/leastrequest/leastrequest.go	87.34% <ø> (ø)
balancer/pickfirst/pickfirst.go	83.95% <ø> (ø)
balancer/rls/internal/adaptive/adaptive.go	100.00% <ø> (ø)
balancer/roundrobin/roundrobin.go	100.00% <100.00%> (ø)
balancer/weightedroundrobin/balancer.go	79.45% <ø> (ø)
internal/backoff/backoff.go	83.33% <ø> (ø)
internal/resolver/dns/dns_resolver.go	89.39% <100.00%> (ø)
internal/transport/http2_server.go	91.03% <100.00%> (+0.09%)	⬆️
... and 8 more

... and 15 files with indirect coverage changes

[easwars]

This is going to be a little painful. But could you please rename this import as rand "math/rand/v2", so that we can track the package name from use sites. Thank you.

[easwars]

Thanks for making these changes.

[arvindbr8]

Sorry should have been faster in reviewing this PR with such a horizontal span. I resolved the conflict.

LGTM! Thanks for taking care of this