[client-v2] Fix proxy configuration globally for the client

[chernser]

Summary

Proxy configuration is copied to client used by operations.

Checklist

Delete items not relevant to your PR:

• Unit and integration tests covering the common scenarios were added

[Paultagoras]

I approved @chernser but could we modify the Proxy tests to tweak the condition we check for? It should be something like this now:

@Test(groups = { "integration" }, enabled = true)
    public void simpleDisabledProxyTest() throws Exception {
        String tableName = "simple_pojo_proxy_table";
        String createSQL = SamplePOJO.generateTableCreateSQL(tableName);
        System.out.println(createSQL);
        createTable(createSQL);

        client.register(SamplePOJO.class, SamplePOJO.generateTableSchema(tableName));
        List<Object> simplePOJOs = new ArrayList<>();

        for (int i = 0; i < 1000; i++) {
            simplePOJOs.add(new SamplePOJO());
        }
        proxy.disable();
        try {
            InsertResponse response = client.insert(tableName, simplePOJOs).get(30, TimeUnit.SECONDS);
        } catch (Exception e) {
            assertTrue(e.getMessage().contains("Operation has likely timed out."));
        }
    }

[mzitnik]

Approving but we still need tests for it @Paultagoras can you add