Drop support for the view-scan optimization (check-in [609fbb94b8f01d67]) as

it was causing multiple performance regressions.  In its place, reduce the
estimated row count for DISTINCT subsqueries by a factor of 8.

FossilOrigin-Name: f911f1c4977fbcae041243955cf2b98d8cc8baa337885a69be0f2b9bd2efa6f3

diff --cc manifest
index 2cc282e161df04d66a4aa2b931e2dfc860b88764,7883893be57913d254e244fdf4aa6c439880cde0..0a0e584fdbc81812c5866dbb3a8cd0030204b03b
--- 1/manifest
--- 2/manifest
+++ b/manifest
@@@ -1,5 -1,5 +1,5 @@@
- C Do\snot\stry\sto\sconvert\sa\sdouble\sinto\san\sunsigned\s64-bit\sinteger,\sas\sthat\sdoes\nnot\swork\son\sall\splatforms.\s\sA\sdouble\scan\sonly\sbe\sconverted\sinto\sa\ssigned\n64-bit\sinteger.
- D 2023-09-15T10:24:29.345
 -C Minor\ssimplification\sto\sthe\sDISTINCT\soutput\srow\scount\schange.
 -D 2023-09-15T19:27:36.965
++C Drop\ssupport\sfor\sthe\sview-scan\soptimization\s(check-in\s[609fbb94b8f01d67])\sas\nit\swas\scausing\smultiple\sperformance\sregressions.\s\sIn\sits\splace,\sreduce\sthe\nestimated\srow\scount\sfor\sDISTINCT\ssubsqueries\sby\sa\sfactor\sof\s8.
++D 2023-09-15T19:51:18.202
  F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
  F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
  F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@@ -2121,9 -2121,8 +2121,9 @@@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a9
  F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
  F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
  F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
- P 858fa236f8b673eb03cf2242e8202cd33ae1f13a43b59bdbb2eecdb21d42ef55 0ab05871ba36e2a0eddfbc700c1d39891c54c453727a4effcdac3327efec163b
- R 471f1110fdf5d26a5080351103b3b730
- T +closed 0ab05871ba36e2a0eddfbc700c1d39891c54c453727a4effcdac3327efec163b
 -P 27390051e86ad86fb35219329d359be9e83073f59782631af7fc519225e10565
++P ce339046416e9ddeffe77f71a8bfb8c5b302160c3207f919aebd62902618ed59 0738386d7c505a98768ddaff7ff1fc76f115882d92d6f84bf136b4aa2caad8b8
+ R 38093a5d0a73ed2782b293b0009addb5
++T +closed 0738386d7c505a98768ddaff7ff1fc76f115882d92d6f84bf136b4aa2caad8b8
  U drh
- Z 5b5a1b021f1cd0ac8b138bf678d74c57
 -Z 00aba278fb7af4364c7414b32687072d
++Z 1f4648241ce7ff62054de9df5d869201
  # Remove this line to create a well-formed Fossil manifest.

diff --cc manifest.uuid
index a478c84dce59cebeb5c456409a25222783d108d1,56368e687cce73c811df1a407e254fa6f044d456..937a9f739dea3d34139b53538942d59d55b92066
--- 1/manifest.uuid
--- 2/manifest.uuid
+++ b/manifest.uuid
@@@ -1,1 -1,1 +1,1 @@@
- ce339046416e9ddeffe77f71a8bfb8c5b302160c3207f919aebd62902618ed59
 -0738386d7c505a98768ddaff7ff1fc76f115882d92d6f84bf136b4aa2caad8b8
++f911f1c4977fbcae041243955cf2b98d8cc8baa337885a69be0f2b9bd2efa6f3