Renamed high-level spam tests to include *_spam_*

These are our current set of general-purpose high-level tests that can
be turned to when needing to test a wide range of filesystem operations.

They were getting a bit hard to keep track of without a consistent
prefix, especially since no individual test suite can actually use all
of them at the same time.

Now, finding these tests is as simple as: ./scripts/test.py -L *_spam_*

I also renamed a couple because their names were starting to get
ridiculous. I mean just look at
test_badblocks_alternating_spam_orphanzombiedir_fuzz...

- *_spam_orphanzombie_fuzz    -> *_spam_oz_fuzz
- *_spam_orphanzombiedir_fuzz -> *_spam_ozd_fuzz
- *_spam_file_pl_fuzz         -> *_spam_f_pl_fuzz
- *_spam_filedir_pl_fuzz      -> *_spam_fd_pl_fuzz

Here are all of the current spam tests and contexts we use them in:

                traversal               badblocks   relocations
                |     gc    ck    grow  |     powerloss   exhaustion
  dir_many      y     y           y     y     y     y
  dir_fuzz      y     y     y     y     y           y     y
  file_many     y     y           y     y     y     y
  file_fuzz     y     y     y     y     y           y     y
  fwrite_fuzz   y     y     y           y                 y
  oz_fuzz       y     y     y     y     y           y     y
  ozd_fuzz      y     y     y     y     y           y     y
  f_pl_fuzz                       y           y     y
  fd_pl_fuzz                      y           y     y

tests/test_powerloss.toml

@@ -21,7 +21,7 @@ after = [
 # We always make progress so this should be O(n) progs, (but maybe
 # O(n^2) reads)
 #
-[cases.test_powerloss_dir_many]
+[cases.test_powerloss_spam_dir_many]
 defines.POWERLOSS_BEHAVIOR = [
     'LFS_EMUBD_POWERLOSS_NOOP',
     'LFS_EMUBD_POWERLOSS_SOMEBITS',
@@ -119,7 +119,7 @@ code = '''
 # We always make progress so this should be O(n) progs, (but maybe
 # O(n^2) reads)
 #
-[cases.test_powerloss_file_many]
+[cases.test_powerloss_spam_file_many]
 defines.POWERLOSS_BEHAVIOR = [
     'LFS_EMUBD_POWERLOSS_NOOP',
     'LFS_EMUBD_POWERLOSS_SOMEBITS',
@@ -219,7 +219,7 @@ code = '''
 # the best. Most likely an internal assert will trigger if anything goes
 # wrong.
 #
-[cases.test_powerloss_file_pl_fuzz]
+[cases.test_powerloss_spam_f_pl_fuzz]
 defines.POWERLOSS_BEHAVIOR = [
     'LFS_EMUBD_POWERLOSS_NOOP',
     'LFS_EMUBD_POWERLOSS_SOMEBITS',
@@ -449,7 +449,7 @@ code = '''
 # the best. Most likely an internal assert will trigger if anything goes
 # wrong.
 #
-[cases.test_powerloss_filedir_pl_fuzz]
+[cases.test_powerloss_spam_fd_pl_fuzz]
 defines.POWERLOSS_BEHAVIOR = [
     'LFS_EMUBD_POWERLOSS_NOOP',
     'LFS_EMUBD_POWERLOSS_SOMEBITS',