fix(tests): make 32-bit GOARCH tests build and run (#9503)
verifyTestFilerClient had bare int64 atomic counters after a map header,
so atomic.AddInt64 panicked with "unaligned 64-bit atomic operation" on
linux/386. Switch to atomic.Int64, which the stdlib guarantees is
8-byte aligned on all platforms.
rpc_version_filter_test.go passed the untyped constant 0xdeadbeef to
t.Errorf, where it default-promoted to int and overflowed 32-bit int.
Bind it to a typed uint32 const used in both the comparison and the
error message.
bfb2661fec