Fix UBSan float-cast-overflow in BridgingTest.numberTest

Summary:
The third assertion in `BridgingTest.numberTest` cast a `double` value of `4294967254.0` (the round-tripped representation of `(uint32_t)-42` through JSI) directly to `int32_t`. Float-to-int conversion is undefined behavior when the value is outside the destination type's range, which UBSan catches on Linux. macOS and Windows builds (without UBSan) silently produced some int value that happened to be != -42, satisfying the `EXPECT_FALSE`.

The remaining two assertions already validate the meaningful round-trip property — that `(uint32_t)-42` survives a trip through JSI and decodes correctly when read back as `uint32_t`. The deleted `EXPECT_FALSE` was effectively documenting "don't cast directly to int32, it's UB" via UB itself, which is not a useful test.

Changelog:
[Internal] - Remove UB-relying assertion from BridgingTest.numberTest

UndefinedBehaviorSanitizer: float-cast-overflow xplat/js/react-native-github/packages/react-native/ReactCommon/react/bridging/tests/BridgingTest.cpp:73:3

Test was never completed. The test process might have crashed.
Buck UI: https://www.internalfb.com/buck2/0e81623b-a566-4181-a630-633a9b0144f5
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Network: Up: 18KiB  Down: 19KiB  (reSessionID-47fd7d68-411c-4457-bd30-9da43be7bd6e)
Loading targets.     Remaining     0/71                                                                                                                                                    1705 dirs read, 2636 targets declared
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Executing actions.   Remaining     0/4161                                                                                                                                                  37:55.2s exec time total
Command: test.     Finished 1 local, 1256 cache (99% hit)                                                                                                                                  37:49.9s exec time cached (99%)                                      
Time elapsed: 8.6s
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Tests finished: Pass 23. Fail 1. Timeout 0. Fatal 0. Skip 0. Omit 0. Infra Failure 0. Build failure 0
1 TESTS FAILED
  ✗ fbsource//xplat/js/react-native-github/packages/react-native/ReactCommon/react/bridging:tests - BridgingTest.numberTest

Run $ fdb buck test <args> to debug fbsource//xplat/js/react-native-github/packages/react-native/ReactCommon/react/bridging:tests - BridgingTest.numberTest
      ^^^ just prefix your previous command! ($ fdb !!)
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[chpurrer@166047.od /data/sandcastle/boxes/fbsource (b6d9fba9d4)]$ 
```

Differential Revision: D103954447

Author: christophpurrer

packages/react-native/ReactCommon/react/bridging/tests/BridgingTest.cpp

@@ -69,11 +69,6 @@ TEST_F(BridgingTest, numberTest) {
       -42,
       static_cast<uint32_t>(
           bridging::toJs(rt, static_cast<uint32_t>(-42)).asNumber()));
-
-  EXPECT_FALSE(
-      -42 ==
-      static_cast<int32_t>(
-          bridging::toJs(rt, static_cast<uint32_t>(-42)).asNumber()));
 }
 
 TEST_F(BridgingTest, stringTest) {