testsuite: increase timeout of ghc-api tests for wasm32

ghc-api tests for wasm32 are more likely to timeout due to the large wasm module sizes, especially when testing with wasm native tail calls, given wasmtime's handling of tail call opcodes are suboptimal at the moment. It makes sense to increase timeout specifically for these tests on wasm32. This doesn't affect other targets, and for wasm32 we don't increase timeout for all tests, so not to risk letting major performance regressions slip through the testsuite.