fix(deps): update module google.golang.org/grpc to v1.81.0

[renovate]

This PR contains the following updates:

Package	Change	Age	Confidence
google.golang.org/grpc	v1.80.0 → v1.81.0

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Release Notes

grpc/grpc-go (google.golang.org/grpc)

v1.81.0: Release 1.81.0

Compare Source

Behavior Changes

• balancer/rls: Switch gauge metrics to asynchronous emission (once per collection cycle) to reduce telemetry noise and align with other gRPC language implementations. (#​8808)

Dependencies

• Minimum supported Go version is now 1.25. (#​8969)

Bug Fixes

• xds: Use the leaf cluster's security config for the TLS handshake instead of the aggregate cluster's config. (#​8956)
• transport: Send a RST_STREAM when receiving an END_STREAM when the stream is not already half-closed. (#​8832)
• xds: Fix ADS resource name validation to prevent a panic. (#​8970)

New Features

• grpc/stats: Add support for custom labels in per-call metrics (gRFC A108). (#​9008)
• xds: Add support for Server Name Indication (SNI) and SAN validation (gRFC A101). Disabled by default. To enable, set GRPC_EXPERIMENTAL_XDS_SNI=true environment variable. (#​9016)
• xds: Add support to control which fields get propagated from ORCA backend metric reports to LRS load reports (gRFC A85). Disabled by default. To enable, set GRPC_EXPERIMENTAL_XDS_ORCA_LRS_PROPAGATION=true. (#​9005)
• xds: Add metrics to track xDS client connectivity and cached resource state (gRFC A78). (#​8807)
• stats/otel: Enhance grpc.subchannel.disconnections metric by adding disconnection reason to the grpc.disconnect_error label (gRFC A94). This provides granular insights into why subchannels are closing. (#​8973)
• mem: Add mem.Buffer.Slice() API to slice the buffer like a slice. (#​8977)
  • Special Thanks: @​ash2k

Performance Improvements

• alts: Pool read buffers to lower memory utilization when sockets are unreadable. (#​8964)
• transport: Pool HTTP/2 framer read buffers to reduce idle memory consumption. Currently limited to Linux for ALTS and non-encrypted transports (TCP, Unix). To disable, set GRPC_GO_EXPERIMENTAL_HTTP_FRAMER_READ_BUFFER_POOLING=false and report any issues. (#​9032)

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