Changing some external testing scripts.

- The absolute path canonifier was overzealously canonifying relevant
  log fields, so it's no longer generally applied to diffing all
  baselines.  I don't think there's any logs that require local
  filesystem path names that aren't already tested by a unit test,
  but if any show up in the future, they can be canonified on a
  case-by-case basis.

- Removed some logs from being diff'd in the diff-all script
  because they're either already covered by a unit test
  (load_scripts.log) or because of difficulty/maintainenance
  tradeoff (prof.log).

Baselines for the external bro-testing repo still need updating.

testing/external/scripts/diff-all

@@ -15,12 +15,14 @@ fi
 rc=0;
 
 for i in $@; do
-    if ! btest-diff $i; then
-       echo "" >>$diag
-       echo "#### btest-diff $i" >>$diag
-       echo "" >>$diag
-       cat $diag.tmp >>$diag
-       rc=1
+    if [[ "$i" != "loaded_scripts.log" && "$i" != "prof.log" ]]; then
+        if ! btest-diff $i; then
+           echo "" >>$diag
+           echo "#### btest-diff $i" >>$diag
+           echo "" >>$diag
+           cat $diag.tmp >>$diag
+           rc=1
+        fi
     fi
 done