Update js-sdk usages around Buffers to avoid needing Buffer polyfill

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

webpack.config.js

@@ -231,8 +231,6 @@ module.exports = (env, argv) => {
 
                 // Polyfill needed by counterpart
                 "util": require.resolve("util/"),
-                // Polyfill needed by matrix-js-sdk/src/crypto
-                "buffer": require.resolve("buffer/"),
                 // Polyfill needed by sentry
                 "process/browser": require.resolve("process/browser"),
             },