gh-38825: Fix two tests that fail on a heavily-loaded machine
    
The commit messages explain each change in detail, but tl;dr these two
tests fail for me when the machine is under heavy load because they are
guessing how long it will take some computation to complete and the
guess is wrong.
    
URL: #38825
Reported by: Michael Orlitzky
Reviewer(s): Tobias Diez

Author: Release Manager

src/sage/parallel/decorate.py

@@ -516,8 +516,6 @@ def fork(f=None, timeout=0, verbose=False):
 
         sage: @fork(timeout=0.1, verbose=True)
         ....: def g(n, m): return factorial(n).ndigits() + m
-        sage: g(5, m=5)
-        8
         sage: g(10^7, m=5)
         Killing subprocess ... with input ((10000000,), {'m': 5}) which took too long
         'NO DATA (timed out)'

src/sage/parallel/map_reduce.py

@@ -1136,21 +1136,12 @@ def start_workers(self):
             sage: from sage.parallel.map_reduce import RESetMapReduce
             sage: def children(x):
             ....:     print(f"Starting: {x}", flush=True)
-            ....:     sleep(float(0.5))
-            ....:     print(f"Finished: {x}", flush=True)
             ....:     return []
             sage: S = RESetMapReduce(roots=[1, 2], children=children)
             sage: S.setup_workers(2)
-            sage: S.start_workers(); sleep(float(0.4))
+            sage: S.start_workers(); sleep(float(5))  # long time
             Starting: ...
             Starting: ...
-            sage: [w.is_alive() for w in S._workers]
-            [True, True]
-            sage: sleep(float(1.5))
-            Finished: ...
-            Finished: ...
-            sage: [not w.is_alive() for w in S._workers]
-            [True, True]
 
         Cleanup::