Update stack trace test goldens to handle engine builds with lazy async stacks (flutter#51216)

The next engine roll will introduce --lazy-async-stacks, which affects the
contents of stack traces.  This updates test expectations to match both the
old and new stack trace formats.

Author: jason-simmons

dev/automated_tests/flutter_test/exception_handling_expectation.txt

@@ -9,7 +9,7 @@ When the exception was thrown, this was the stack:
 #(1|2)      .+ \(package:flutter_test[/\\]src[/\\]widget_tester\.dart:[0-9]+:[0-9]+\)
 <asynchronous suspension>
 <<skip until matching line>>
-^\(elided [0-9]+ frames.+$
+^\(elided ([0-9]+|one) frame.+$
 <<skip until matching line>>
 The test description was:
 Exception handling in test harness - string
@@ -29,7 +29,7 @@ When the exception was thrown, this was the stack:
 #(1|2)      .+ \(package:flutter_test[/\\]src[/\\]widget_tester\.dart:[0-9]+:[0-9]+\)
 <asynchronous suspension>
 <<skip until matching line>>
-^\(elided [0-9]+ .+$
+^\(elided ([0-9]+|one) .+$
 <<skip until matching line>>
 The test description was:
 Exception handling in test harness - FlutterError
@@ -52,7 +52,7 @@ When the exception was thrown, this was the stack:
 <<skip until matching line>>
 #[0-9]+ +.+ \(package:flutter_test[/\\]src[/\\]widget_tester\.dart:[0-9]+:[0-9]+\)
 <<skip until matching line>>
-^\(elided [0-9]+ .+$
+^\(elided ([0-9]+|one) .+$
 <<skip until matching line>>
 The test description was:
 Exception handling in test harness - uncaught Future error

dev/automated_tests/flutter_test/test_async_utils_unguarded_expectation.txt

@@ -15,11 +15,11 @@ statement in front of the call to the first\.
 
 When the first method was called, this was the stack:
 <<skip until matching line>>
-(elided [0-9]+ frames from .+)
+(elided ([0-9]+|one) frames? from .+)
 
 When the exception was thrown, this was the stack:
 <<skip until matching line>>
-(elided [0-9]+ frames from .+)
+(elided ([0-9]+|one) frames? from .+)
 
 The test description was:
 TestAsyncUtils - handling unguarded async helper functions