bazel: rename @com_github_cncf_udpa to @com_github_cncf_xds

[sergiitk]

The repo has been renamed from cncf/udpa to cncf/xds long time ago, this is just to reflect this in the bazel repo name.
Otherwise this is a noop.

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Commit Message: bazel: rename @com_github_cncf_udpa to @com_github_cncf_xds
Additional Description:

The repo has been renamed from cncf/udpa to cncf/xds long time ago, this is just to reflect this in the bazel repo name.
Otherwise this is a noop.

Risk Level: Low
Testing: do_ci.sh
Docs Changes: N/A (except some md files got updated)
Release Notes: N/A
Platform Specific Features: N/A

[repokitteh-read-only]

CC @envoyproxy/api-shepherds: Your approval is needed for changes made to (api/envoy[\w/]*/(v1alpha\d?|v1|v2alpha\d?|v2))|(api/envoy/type/(matcher/)?\w+.proto).
CC @envoyproxy/api-shepherds: Your approval is needed for changes made to (api/envoy/|docs/root/api-docs/).
envoyproxy/api-shepherds assignee is @lizan
CC @envoyproxy/api-watchers: FYI only for changes made to (api/envoy/|docs/root/api-docs/).
CC @envoyproxy/dependency-shepherds: Your approval is needed for changes made to (bazel/.*repos.*\.bzl)|(bazel/dependency_imports\.bzl)|(api/bazel/.*\.bzl)|(.*/requirements\.txt)|(.*\.patch).
envoyproxy/dependency-shepherds assignee is @htuch

🐱

Caused by: #30802 was opened by sergiitk.

see: more, trace.

[sergiitk]

Addresses good point brought in #30159 (comment).

cc @moderation @phlax

[phlax]

lgtm, with the stub to maintain downstream compat

im wondering if there is a way to add a deprecated notice

[htuch]

LGTM, thanks!

[sergiitk]

For future references, corresponding downstream compat fix in grpc core: grpc/grpc#35603. Thanks @eugeneo!