ci: don't delete test.json.txt after processing

We've seen some issues where Bazel jobs are failing in `github-post`
(cockroachdb#73841, cockroachdb#74013) with the following output:

    found outstanding output. Considering last test failed:

It's hard to say what the problem is because these scripts haven't kept
the `test.json.txt` in `artifacts`. Here I remove the logic to clean up
the file so we can RC further instances of the problem.

Release note: None

build/teamcity-bazel-support.sh

@@ -48,7 +48,7 @@ _tc_release_branch() {
 #   `$BAZEL_BIN/pkg/cmd/github-post/github-post_/github-post`
 # artifacts_dir: usually `/artifacts`
 # test_json: path to test's JSON output, usually generated by `rules_go`'s and
-#   `GO_TEST_JSON_OUTPUT_FILE`. The file is removed after processing.
+#   `GO_TEST_JSON_OUTPUT_FILE`.
 # create_tarball: whether to create a tarball with full logs. If the test's
 #   exit code is passed, the tarball is generated on failures.
 process_test_json() {
@@ -58,12 +58,6 @@ process_test_json() {
   local test_json=$4
   local create_tarball=$5
 
-  # move test.json.txt to the artifacts directory in order to simplify tarball creation
-  if [ ! -e $artifacts_dir/test.json.txt ]; then
-    mv -f $test_json $artifacts_dir/test.json.txt
-    test_json=$artifacts_dir/test.json.txt
-  fi
-
   $testfilter -mode=strip < "$test_json" | $testfilter -mode=omit | $testfilter -mode=convert > "$artifacts_dir"/failures.txt
   failures_size=$(stat --format=%s "$artifacts_dir"/failures.txt)
   if [ $failures_size = 0 ]; then
@@ -103,8 +97,6 @@ process_test_json() {
     rm -rf "$artifacts_dir"/full_output.txt
   fi
 
-  rm -f "$test_json"
-
   # Some unit tests test automatic ballast creation. These ballasts can be
   # larger than the maximum artifact size. Remove any artifacts with the
   # EMERGENCY_BALLAST filename.

build/teamcity/cockroach/nightlies/stress_impl.sh

@@ -15,7 +15,6 @@ fi
 bazel build //pkg/cmd/bazci //pkg/cmd/github-post //pkg/cmd/testfilter --config=ci
 BAZEL_BIN=$(bazel info bazel-bin --config=ci)
 ARTIFACTS_DIR=/artifacts
-GO_TEST_JSON_OUTPUT_FILE=$ARTIFACTS_DIR/test.json.txt
 
 # Query to list all affected tests.
 PKG=${PKG#"./"}
@@ -34,6 +33,7 @@ do
         continue
     fi
     exit_status=0
+    GO_TEST_JSON_OUTPUT_FILE=$ARTIFACTS_DIR/$(echo "$test" | cut -d: -f2).test.json.txt
     $BAZEL_BIN/pkg/cmd/bazci/bazci_/bazci --config=ci test "$test" -- \
                                           --test_env=COCKROACH_NIGHTLY_STRESS=true \
                                           --test_env=GO_TEST_JSON_OUTPUT_FILE=$GO_TEST_JSON_OUTPUT_FILE \