Increase initial value sample count in `WorksWithSeeds` tests to deflake.

PiperOrigin-RevId: 1002482158

domain_tests/map_filter_combinator_test.cc

diff --git a/domain_tests/map_filter_combinator_test.cc b/domain_tests/map_filter_combinator_test.cc
index e45050d..b0bf7b9 100644
--- a/domain_tests/map_filter_combinator_test.cc
+++ b/domain_tests/map_filter_combinator_test.cc
@@ -173,7 +173,7 @@
                               InRange(0, 1000000))
                     .WithSeeds({8});
 
-  EXPECT_THAT(GenerateInitialValues(domain, 20), Contains(8));
+  EXPECT_THAT(GenerateInitialValues(domain, 1000), Contains(8));
   EXPECT_THAT(domain.FromValue(7), Eq(std::nullopt));
 }
 
@@ -533,8 +533,8 @@
                         InRange(2, 5))
           .WithSeeds({"ABC", "WXYZ"});
 
-  EXPECT_THAT(GenerateInitialValues(domain, 20), Contains("ABC"));
-  EXPECT_THAT(GenerateInitialValues(domain, 20), Contains("WXYZ"));
+  EXPECT_THAT(GenerateInitialValues(domain, 1000), Contains("ABC"));
+  EXPECT_THAT(GenerateInitialValues(domain, 1000), Contains("WXYZ"));
 }
 
 TEST(ReversibleFlatMap, FromValueReturnsNulloptWhenInverseOrConstraintsFail) {