wasm: update Wasmtime to v0.26. (#15882)
wasm: update Wasmtime to v0.26. (#15882)

Performance improved ~10% in microbenchmarks (compared to v0.25):

Benchmark                                                       Diff
--------------------------------------------------------------------
WasmSpeedTest_empty                                          -0.1513
WasmSpeedTest_get_current_time                               -0.0328
WasmSpeedTest_small_string                                   -0.1145
WasmSpeedTest_small_string1000                               -0.0697
WasmSpeedTest_small_string_check_compiler                    -0.1039
WasmSpeedTest_small_string_check_compiler1000                -0.0966
WasmSpeedTest_large_string                                   -0.0623
WasmSpeedTest_large_string1000                               -0.0689
WasmSpeedTest_get_property                                   -0.1385
WasmSpeedTest_grpc_service                                   -0.1250
WasmSpeedTest_grpc_service1000                               -0.1917
WasmSpeedTest_modify_metadata                                -0.0297
WasmSpeedTest_modify_metadata1000                            -0.0318
WasmSpeedTest_json_serialize                                 -0.0920
WasmSpeedTest_json_deserialize                               -0.0723
WasmSpeedTest_json_deserialize_empty                         -0.1481
WasmSpeedTest_convert_to_filter_state                        -0.1074

Signed-off-by: Piotr Sikora <ba6f3a1a6d7e1ecae91b31e93969cc392fbd0fdd@google.com>
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