refactor: Adapt SDK spans to use the kind parameter

[GSVarsha]

For the following code snippet,

import instana
from instana.singletons import tracer

import requests
from opentelemetry.trace import SpanKind

with tracer.start_as_current_span("test-span", kind=SpanKind.SERVER) as span:
    response = requests.get("https://www.httpbin.org/get")
    print(response.json())

Before the fix

For custom ENTRY span:

• Sub calls: 3
• The kind parameter of start_span has no effect

After the fix

For custom ENTRY span:

• Sub calls: 2
• The kind parameter of start_span reflected in span.kind as expected

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[pvital]

It looks good to me.