Summary:
The `go get` for the grpc server and client binaries was fetching
the entire repo as a dependency to handle the proto import. Instead package up
the proto file (and the corresponding gen file since we have it anyway) into a
container layer and add it to the images. This removes the need to fetch the
repo to get the proto. (Though we still fetch the other deps on demand).

Test Plan:
All existing tests will pass. Ensured that the generated binaries
function as expected and the filesystem in those containers no longer includes
a `px.dev/pixie` in the `go/mod` download folder.

Reviewers: oazizi, zasgar

Reviewed By: oazizi, zasgar
Signed-off-by: Vihang Mehta <vihang@pixielabs.ai>

Differential Revision: https://phab.corp.pixielabs.ai/D10782

GitOrigin-RevId: f2b51ddb5dcdd5cc63c154d3124e02064731cfe9