Renumber confusing value for GUC_UNIT_BYTE

It had a power-of-two value, which looks right, and causes the other
values which aren't powers-of-two to look wrong.  But this is tested
for equality and not a bitwise test.

See also:
6e7baa3
https://www.postgresql.org/message-id/CAOG9ApEu8bXVwBxkOO9J7ZpM76TASK_vFMEEiCEjwhMmSLiaqQ%40mail.gmail.com

Author: Justin Pryzby <pryzby@telsasoft.com>
Discussion: https://www.postgresql.org/message-id/flat/20220720145220.GJ12702@telsasoft.com

Author: petere

src/include/utils/guc.h

@@ -223,7 +223,7 @@ typedef enum
 #define GUC_UNIT_BLOCKS			0x2000	/* value is in blocks */
 #define GUC_UNIT_XBLOCKS		0x3000	/* value is in xlog blocks */
 #define GUC_UNIT_MB				0x4000	/* value is in megabytes */
-#define GUC_UNIT_BYTE			0x8000	/* value is in bytes */
+#define GUC_UNIT_BYTE			0x5000	/* value is in bytes */
 #define GUC_UNIT_MEMORY			0xF000	/* mask for size-related units */
 
 #define GUC_UNIT_MS			   0x10000	/* value is in milliseconds */