patch 8.1.0925: terminal scrollback test still still flaky

Problem:    Terminal scrollback test still still flaky.
Solution:   Explicitly set the shell.  Disable ruler. (Ozaki Kiichi,
            closes #3966)
diff --git a/src/testdir/dumps/Test_terminal_01.dump b/src/testdir/dumps/Test_terminal_01.dump
index 4a0014f..a242bb7 100644
--- a/src/testdir/dumps/Test_terminal_01.dump
+++ b/src/testdir/dumps/Test_terminal_01.dump
@@ -7,7 +7,7 @@
 |4|8| @72
 >4|9| @72
 |~+0#4040ff13&| @73
-|!+2#ffffff16#00e0003|/|b|i|n|/|t|c|s|h| |[|T|e|r|m|i|n|a|l|]| @35|5|1|,|1| @10|B|o|t
+|!+2#ffffff16#00e0003|/|b|i|n|/|s|h| |[|T|e|r|m|i|n|a|l|]| @55
 | +0#0000000#ffffff0@74
 |~+0#4040ff13&| @73
 |~| @73
@@ -16,5 +16,5 @@
 |~| @73
 |~| @73
 |~| @73
-|[+1#0000000&|N|o| |N|a|m|e|]| @47|0|,|0|-|1| @9|A|l@1
+|[+1#0000000&|N|o| |N|a|m|e|]| @65
 | +0&&@74