Fix an error in the aggregate query LEFT JOIN flattening optimization from

[2cf373b10c9bc4cb] and further enhance that optimization so that it works
even if there is a GROUP BY clause.

FossilOrigin-Name: b52393ac28debe9867227f901d05cccf54f1b467272474500a549d956a5fb4d7

diff --cc manifest
index c38bca3b5eff4ad586a3272741b0ab7df025af96,a5d100a7291c1eaaa2519feeb1a628ae68eb153a..40e61117744fea80bdfc025f9e1f58a36006d11c
--- 1/manifest
--- 2/manifest
+++ b/manifest
@@@ -1,5 -1,5 +1,5 @@@
- C Reduce\sa\stimeout\sin\swalsetlk.test\sfrom\s2000ms\sto\s1100ms\sso\sthat\sthe\stest\sruns\sa\sbit\sfaster.
- D 2022-07-25T11:04:13.326
 -C Allow\ssubqueries\son\sthe\sright-hand\sside\sof\sa\sLEFT\sJOIN\sto\sbe\sflattened\seven\nif\sthey\scontain\sa\sGROUP\sBY\sclause.
 -D 2022-07-25T15:54:23.818
++C Fix\san\serror\sin\sthe\saggregate\squery\sLEFT\sJOIN\sflattening\soptimization\sfrom\n[2cf373b10c9bc4cb]\sand\sfurther\senhance\sthat\soptimization\sso\sthat\sit\sworks\neven\sif\sthere\sis\sa\sGROUP\sBY\sclause.
++D 2022-07-25T16:06:14.582
  F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
  F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
  F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@@ -1981,8 -1981,8 +1981,9 @@@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a9
  F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
  F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
  F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
- P a995614b9aedf4492e6d7b777293770f268837f8246e1678ef0523738c8a8339
- R e7b8638d6eb2bb65a2c18035ce7a719d
- U dan
- Z 34c5d50caba419fff3085e94b713365e
 -P 40d08807209638aad728be2cedbc904e342e76c8e486c364bd571b55dd2e1e87
++P 836fa097060dadeb2dc5d4ee2e40621c4af606b1ef7241e2264823e23e4ceb1f 816da9a893ae97a21463562479edb419a8b511ae731d86eccee3fa6e3e7dc96e
+ R 9e57786ca604cfa312cb51673a055fc9
++T +closed 816da9a893ae97a21463562479edb419a8b511ae731d86eccee3fa6e3e7dc96e
+ U drh
 -Z fc9a3eeded753547b019835285a3d918
++Z c715e74c49fbf8938da5e0c5419cf34a
  # Remove this line to create a well-formed Fossil manifest.

diff --cc manifest.uuid
index 69076e5991a72453809b5ad72fdc94f44063725c,790aa223e46a073d520961d3dfb509bf9b33aff6..b115932a65fd88134cad4cb69665c644a3146a77
--- 1/manifest.uuid
--- 2/manifest.uuid
+++ b/manifest.uuid
@@@ -1,1 -1,1 +1,1 @@@
- 836fa097060dadeb2dc5d4ee2e40621c4af606b1ef7241e2264823e23e4ceb1f
 -816da9a893ae97a21463562479edb419a8b511ae731d86eccee3fa6e3e7dc96e
++b52393ac28debe9867227f901d05cccf54f1b467272474500a549d956a5fb4d7