[wasm] Do not use link flags for bitcode compilation

Backport of (dotnet#101397)

This avoids errors like:

    /root/helix/work/correlation/build/wasm-shared/WasmApp.Common.targets(832,5): error : emcc: warning: linker setting ignored during compilation: 'EXPORT_ES6' [-Wunused-command-line-argument] [/root/helix/work/workitem/e/publish/ProxyProjectForAOTOnHelix.proj]
    /root/helix/work/correlation/build/wasm-shared/WasmApp.Common.targets(832,5): error : emcc: warning: linker setting ignored during compilation: 'EXPORT_EXCEPTION_HANDLING_HELPERS' [-Wunused-command-line-argument] [/root/helix/work/workitem/e/publish/ProxyProjectForAOTOnHelix.proj]

This should helps with known build error dotnet#104827
where the warning can hide another errors

src/mono/wasm/build/WasmApp.Native.targets

@@ -398,10 +398,11 @@
 
   <Target Name="_WasmWriteRspForCompilingBitcode">
     <ItemGroup>
-      <_BitcodeLDFlags Include="@(_EmccLDFlags)" />
-      <_BitcodeLDFlags Include="$(EmccExtraBitcodeLDFlags)" />
+      <_BitcodeCompileFlags Include="$(EmccLinkOptimizationFlag)" />
+      <_BitcodeCompileFlags Include="@(_EmccCommonFlags)" />
+      <_BitcodeCompileFlags Include="$(EmccExtraBitcodeLDFlags)" />
     </ItemGroup>
-    <WriteLinesToFile Lines="@(_BitcodeLDFlags)" File="$(_EmccCompileBitcodeRsp)" Overwrite="true" WriteOnlyWhenDifferent="true" />
+    <WriteLinesToFile Lines="@(_BitcodeCompileFlags)" File="$(_EmccCompileBitcodeRsp)" Overwrite="true" WriteOnlyWhenDifferent="true" />
     <ItemGroup>
       <FileWrites Include="$(_EmccCompileBitcodeRsp)" />
     </ItemGroup>