Remove remaining expected file for Python 2.2

We don't have complete expected coverage for Python 2.2 anyway, so it
doesn't seem worth keeping this one around that no one appears to be
updating anyway.  Visual inspection of the differences ought to be
good enough for those few who care about this obsolete Python version.

Author: petere

src/pl/plpython/expected/README

@@ -2,9 +2,11 @@ Guide to alternative expected files:
 
 plpython_error_0.out		Python 2.4 and older
 
-plpython_unicode.out		any version, when server encoding != SQL_ASCII and client encoding = UTF8; else ...
-plpython_unicode_0.out		any version, when server encoding != SQL_ASCII and client encoding != UTF8; else ...
-plpython_unicode_2.out		Python 2.2
-plpython_unicode_3.out		Python 2.3 through 3.1
+plpython_unicode.out		server encoding != SQL_ASCII and client encoding == UTF8; else ...
+plpython_unicode_0.out		server encoding != SQL_ASCII and client encoding != UTF8; else ...
+plpython_unicode_3.out		server encoding == SQL_ASCII
 
-plpython_types_3.out		Python 3.1
+plpython_types_3.out		Python 3.x
+
+Note: Building with Python 2.2 is supported, but there are no expected
+files for it (too much work to maintain).