Exclude some run-tests exercising VarHandles from automated executions.

Disable the following tests (for which build support has been newly
added), as the ART run-test TradeFed test runner does not (yet)
support some features required by these tests:

* `art-run-test-1981-structural-redef-private-method-handles`
* `art-run-test-1983-structural-redefinition-failures`

Test: atest --test-mapping art:presubmit
Bug: 147812905
Change-Id: Ia3118bd1f541b29bb41761adc01e7378f979d1a2
diff --git a/test/utils/regen-test-files b/test/utils/regen-test-files
index d9d54e2..0ba75d1 100755
--- a/test/utils/regen-test-files
+++ b/test/utils/regen-test-files
@@ -185,7 +185,11 @@
   "1978-regular-obsolete-then-structural-obsolescence",
   "1979-threaded-structural-transformation",
   "1980-obsolete-object-cleared",
+  # 1981-structural-redef-private-method-handles: Custom `run` script.
+  "1981-structural-redef-private-method-handles",
   "1982-no-virtuals-structural-redefinition",
+  # 1983-structural-redefinition-failures: Custom `run` script.
+  "1983-structural-redefinition-failures",
   "1984-structural-redefine-field-trace",
   "1985-structural-redefine-stack-scope",
   "1986-structural-redefine-multi-thread-stack-scope",
@@ -344,6 +348,7 @@
   "985-re-obsolete",
   "986-native-method-bind",
   "987-agent-bind",
+  # 988-method-trace: Custom `run` script.
   "988-method-trace",
   "989-method-trace-throw",
   "990-field-trace",