Upgrade vendored grpc to remove vulnerabilities coming from netty

[milindl]

Currently we use this version of grpc

beam/buildSrc/src/main/groovy/org/apache/beam/gradle/GrpcVendoring_1_69_0.groovy

Line 35 in 15f973f

static def grpc_version = "1.69.0"

Along with this, we get Netty version 4.1.110.Final

https://github.com/grpc/grpc-java/blob/v1.69.0/gradle/libs.versions.toml#L2

There are vulnerabilities in this version like CVE-2026-42578, CVE-2026-42587, CVE-2026-42583, CVE-2025-58057, CVE-2025-67735 and many more.