Regression test for sync psync crash (#10288)

Added regression tests for #10020 / #10081 / #10243.
The above PRs fixed some crashes due to an asserting,
see function `clientHasPendingReplies` (introduced in #9166).

This commit added some tests to cover the above scenario.
These tests will all fail in #9166, althought fixed not,
there is value in adding these tests to cover and verify
the changes. And it also can cover #8868 (verify the logs).

Other changes: 
1. Reduces the wait time in `waitForBgsave` and `waitForBgrewriteaof`
from 1s to 50ms, which should reduce the time for some tests.
2. Improve the test infra to print context when `assert_match` fails.
3. Improve the test infra to print `$error` when `assert_error` fails.
```
Expected an error matching 'ERR*' but got 'OK' (context: type eval line 4 cmd {assert_error "ERR*" {r set a b}} proc ::test)
```

2 files changed, 6 insertions, 6 deletions

diff --git a/tests/support/test.tcl b/tests/support/test.tcl
index db3a81e06..f5de12256 100644
--- a/tests/support/test.tcl
+++ b/tests/support/test.tcl
@@ -24,10 +24,10 @@ proc assert_no_match {pattern value} {
     }
 }
 
-proc assert_match {pattern value} {
+proc assert_match {pattern value {detail ""}} {
     if {![string match $pattern $value]} {
         set context "(context: [info frame -1])"
-        error "assertion:Expected '$value' to match '$pattern' $context"
+        error "assertion:Expected '$value' to match '$pattern' $context $detail"
     }
 }
 
@@ -84,9 +84,9 @@ proc assert_range {value min max {detail ""}} {
 
 proc assert_error {pattern code {detail ""}} {
     if {[catch {uplevel 1 $code} error]} {
-        assert_match $pattern $error
+        assert_match $pattern $error $detail
     } else {
-        assert_failed "assertion:Expected an error but nothing was caught" $detail
+        assert_failed "Expected an error matching '$pattern' but got '$error'" $detail
     }
 }
 
diff --git a/tests/support/util.tcl b/tests/support/util.tcl
index 9d1a127ed..46c9654c8 100644
--- a/tests/support/util.tcl
+++ b/tests/support/util.tcl
@@ -89,7 +89,7 @@ proc waitForBgsave r {
                 puts -nonewline "\nWaiting for background save to finish... "
                 flush stdout
             }
-            after 1000
+            after 50
         } else {
             break
         }
@@ -103,7 +103,7 @@ proc waitForBgrewriteaof r {
                 puts -nonewline "\nWaiting for background AOF rewrite to finish... "
                 flush stdout
             }
-            after 1000
+            after 50
         } else {
             break
         }