[Bazel] Swap stray td_srcs to deps

[GMNGeoffrey]

Summary

This is the last instance of td_srcs in MLIR core build files. deps is
generally preferred. There are still some cases where td_srcs is
useful where creating a td_library would just be another layer of
indirection, so not (yet) dropping it entirely.

utils/bazel/llvm-project-overlay/mlir/test/BUILD.bazel

tbl_outs = [
         ),
         (
             ["-gen-attrdef-defs"],
             "lib/Dialect/Test/TestAttrDefs.cpp.inc",
         ),
     ],
     tblgen = "//mlir:mlir-tblgen",
     td_file = "lib/Dialect/Test/TestAttrDefs.td",
-    td_srcs = [
+    test = True,
+    deps = [
         ":TestOpTdFiles",
     ],
-    test = True,
 )
 
 gentbl_cc_library(
     name = "TestTypeDefsIncGen",
     strip_include_prefix = "lib/Dialect/Test",
     tbl_outs = [
         (
             [