Improve test labels for binary interface file size tests

Test labels for binary interface file sizes are hard to read and overly
verbose at the same time. Extend the name for the metric title, but
shorten it in the actual comparison table.

testsuite/driver/testutil.py

@@ -160,5 +160,8 @@ def shorten_metric_name(name: str) -> str:
         "compile_time/bytes allocated": "ghc/alloc",
         "compile_time/peak_megabytes_allocated": "ghc/peak",
         "compile_time/max_bytes_used": "ghc/max",
+        "binary_size/if_compression(1)": "size/1",
+        "binary_size/if_compression(2)": "size/2",
+        "binary_size/if_compression(3)": "size/3",
     }
     return dic.get(name, name)

testsuite/tests/iface/all.T

 test( 'if_faststring'
-    , [ stat_from_file('if_compression(1)', 5, 'NORMALSIZE')
-      , stat_from_file('if_compression(2)', 5, 'MEDIUMSIZE')
-      , stat_from_file('if_compression(3)', 5, 'FULLSIZE')
+    , [ stat_from_file('binary_size/if_compression(1)', 5, 'NORMALSIZE')
+      , stat_from_file('binary_size/if_compression(2)', 5, 'MEDIUMSIZE')
+      , stat_from_file('binary_size/if_compression(3)', 5, 'FULLSIZE')
       , extra_files(["Lib.hs"])]
     , compile_and_run
     , ['-package ghc'])
 
 test( 'if_name'
-    , [ stat_from_file('if_compression(1)', 5, 'NORMALSIZE')
-      , stat_from_file('if_compression(2)', 5, 'MEDIUMSIZE')
-      , stat_from_file('if_compression(3)', 5, 'FULLSIZE')
+    , [ stat_from_file('binary_size/if_compression(1)', 5, 'NORMALSIZE')
+      , stat_from_file('binary_size/if_compression(2)', 5, 'MEDIUMSIZE')
+      , stat_from_file('binary_size/if_compression(3)', 5, 'FULLSIZE')
       , extra_files(["Lib.hs", "IfaceSharingName.hs"])]
     , compile_and_run
     , ['-package ghc'])
 
 test( 'if_ifacetype'
-    , [ stat_from_file('if_compression(1)', 5, 'NORMALSIZE')
-      , stat_from_file('if_compression(2)', 5, 'MEDIUMSIZE')
-      , stat_from_file('if_compression(3)', 5, 'FULLSIZE')
+    , [ stat_from_file('binary_size/if_compression(1)', 5, 'NORMALSIZE')
+      , stat_from_file('binary_size/if_compression(2)', 5, 'MEDIUMSIZE')
+      , stat_from_file('binary_size/if_compression(3)', 5, 'FULLSIZE')
       , extra_files(["Lib.hs", "IfaceSharingIfaceType.hs"])]
     , compile_and_run
     , ['-package ghc'])