Fix unnecessary build reruns caused by tonic bug

[koxu1996]

I had hard time using gevulot-rs as dependency, as every change required 5 seconds for intellisense to pick up. This was caused by upstream bug in tonic builder - see Valensas/tonic-buf-build#7.

This PR workarounds it, by disabling all rerun-if-changed emits from tonic builder, and emittitng the valid one manually (hardcoded proto path).

[koxu1996]

Subsequent build time - before PR:

$ cargo build
   Compiling gevulot-rs v0.1.3 (/tmp/gevulot-rs)
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 4.88s

Subsequent build time - after PR:

$ cargo build
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.12s