Add scheme to loki client

[sed-i]

Currently the client code has http hard-coded:

loki-k8s-operator/src/loki_server.py

Line 41 in 5a826f1

self.base_url = f"http://{self.host}:{self.port}"

Ref: https://github.com/canonical/prometheus-k8s-operator/blob/d33f51f39d990de3b8dcb9436bf69291a8e8b891/src/prometheus_client.py#L20

[Abuelodelanada]

We do not need TLS for this.
This is almost dead code. Right now we are using self.base_url to get the build_info through a request:

loki-k8s-operator/src/loki_server.py

Line 44 in 5a826f1

def _build_info(self):

And with that build_info we get Loki's version:

loki-k8s-operator/src/loki_server.py

Line 62 in 5a826f1

def version(self) -> str:

We can get Loki's version using the binary. An example of this in Grafana agent:

    def agent_version_output(self) -> str:
        """Runs `agent -version` and returns the output.

        Returns:
            Output of `agent -version`
        """
        version_output, _ = self._container.exec(["/bin/agent", "-version"]).wait_output()
        return version_output

[Abuelodelanada]

This is definitely dead code, we are in fact using:

https://github.com/canonical/loki-k8s-operator/blob/main/src/charm.py#L509

    @property
    def _loki_version(self) -> Optional[str]:
        """Returns the version of Loki.

        Returns:
            A string equal to the Loki version
        """
        if not self._container.can_connect():
            return None
        version_output, _ = self._container.exec(["/usr/bin/loki", "-version"]).wait_output()
        # Output looks like this:
        # loki, version 2.4.1 (branch: HEAD, ...
        result = re.search(r"version (\d*\.\d*\.\d*)", version_output)
        if result is None:
            return result
        return result.group(1)