Update the max size of protodelim.Unmarshal to 64MB

[yushan8]

Why?

• Unmarshalling the proto with protodelim.UnmarshalFrom causes the proto max size to exceed on large query output error: run 1: query failed: proto: : message size 5531512 exceeded unmarshaler's maximum configured size 4194304
• This error is not surfaced because the command hangs from reading from the stdout pipe. We should flush out the rest of the pipe to avoid the command from hanging.

What?

• Keep reading from stdout until the stdout pipe is drained to avoid the command from hanging
• Update the max proto size to 64MB

Test Plan

INFO: Running command line: bazel-bin/example/cmd/query-bench/query-bench_/query-bench <args omitted>
workspace:  /home/user/go-code
query:      //external:all-targets + deps(//...:all-targets)
runs:       1

2026-02-25T23:26:38.754Z        INFO    bazel/query.go:25       Querying Bazel{workspacePath 15 0 /home/user/go-code <nil>} {query 15 0 //external:all-targets + deps(//...:all-targets) <nil>}
2026-02-25T23:27:28.085Z        DEBUG   bazel/query.go:85       Parsed 2353361 targets from bazel query
run 1: bazel query: 49.332s  (2353361 targets)
run 1: targethasher: 43.097s  (2353616 targets)