Small simplification of the gapic/src/main BUILD.bazel.
Small simplification of the gapic/src/main BUILD.bazel.

google/gapid,pmuetschard/gapid,pmuetschard/gapid,google/agi,google/agi,pmuetschard/gapid,Qining/gapid,google/gapid,google/gapid,google/agi,google/gapid,google/agi,google/agi,google/agi,Qining/gapid,Qining/gapid,google/gapid,Qining/gapid,Qining/gapid,Qining/gapid,google/agi,pmuetschard/gapid,pmuetschard/gapid,pmuetschard/gapid,Qining/gapid,Qining/gapid,pmuetschard/gapid,google/gapid,google/gapid,pmuetschard/gapid,google/agi,google/gapid