[bazel][mlir] Build Debug/BreakpointManagers only from a single target

When writing 5f2b0892 "[bazel][mlir] BreakpointManager fixes for 7f069f5e",
I did not notice that 17c6de3f "[bazel] Fix bazel build for 7f069f5e.."
had added Debug/BreakpointManagers globs to the Debug target. But these
are already being built in the "BreakpointManagers" target; remove them
from "Debug".