tests: remove redundant remote tests

With introduction of https://github.com/iterative/dvc-plugins,
all important tests are being ran there, so there is no need
for dvc repo to run them again.

This PR also removes some redundant/broken remote tests.

tests/utils/httpd.py

@@ -1,91 +0,0 @@
-import hashlib
-import os
-import threading
-from contextlib import contextmanager
-from http import HTTPStatus
-from http.server import HTTPServer
-
-from RangeHTTPServer import RangeRequestHandler
-
-
-class TestRequestHandler(RangeRequestHandler):
-    def __init__(self, *args, **kwargs):
-        super().__init__(*args, **kwargs)
-
-    def end_headers(self):
-        # RangeRequestHandler only sends Accept-Ranges header if Range header
-        # is present, see https://github.com/danvk/RangeHTTPServer/issues/23
-        if not self.headers.get("Range"):
-            self.send_header("Accept-Ranges", "bytes")
-
-        # Add a checksum header
-        file = self.translate_path(self.path)
-
-        if not os.path.isdir(file) and os.path.exists(file):
-            with open(file, encoding="utf-8") as fd:
-                encoded_text = fd.read().encode("utf8")
-                checksum = hashlib.md5(encoded_text).hexdigest()
-                self.send_header("Content-MD5", checksum)
-
-        RangeRequestHandler.end_headers(self)
-
-    def _chunks(self):
-        while True:
-            data = self.rfile.readline(65537)
-            chunk_size = int(data[:-2], 16)
-            if chunk_size == 0:
-                return
-            data = self.rfile.read(chunk_size)
-            yield data
-            self.rfile.read(2)
-
-    def do_POST(self):
-        chunked = self.headers.get("Transfer-Encoding", "") == "chunked"
-        path = self.translate_path(self.path)
-        try:
-            os.makedirs(os.path.dirname(path), exist_ok=True)
-            with open(path, "wb") as fd:
-                if chunked:
-                    for chunk in self._chunks():
-                        fd.write(chunk)
-                else:
-                    size = int(self.headers.get("Content-Length", 0))
-                    fd.write(self.rfile.read(size))
-        except OSError as e:
-            self.send_error(HTTPStatus.INTERNAL_SERVER_ERROR, str(e))
-        self.send_response(HTTPStatus.OK)
-        self.end_headers()
-
-
-@contextmanager
-def run_server_on_thread(server):
-    thread = threading.Thread(target=server.serve_forever)
-    thread.daemon = True
-    thread.start()
-
-    yield server
-
-    server.socket.close()
-    server.shutdown()
-    server.server_close()
-
-
-class StaticFileServer:
-    _lock = threading.Lock()
-
-    def __init__(self, directory):
-        from functools import partial
-
-        addr = ("localhost", 0)
-        req = partial(TestRequestHandler, directory=directory)
-        server = HTTPServer(addr, req)
-        self.runner = run_server_on_thread(server)
-
-    # pylint: disable=no-member
-    def __enter__(self):
-        self._lock.acquire()
-        return self.runner.__enter__()
-
-    def __exit__(self, *args):
-        self.runner.__exit__(*args)
-        self._lock.release()