[Tracing Framework] Fix parent span setting in case multiple tasks are created from a single thread

[Gaganjuneja]

Is your feature request related to a problem? Please describe.
Addresses the issue with code change #7543
For an instance where multiple tasks are being submitted from a loop the parent span is getting wrongly set.

Example :-
Parent - A

for(int i=0; i<array["B", "C", "D", "E"].length; i++){
       performPhaseOnShard(array[i]);
}

performPhaseOnShard executes the phase on the node where the shard is located, it could be locally or external data node. If we start a span from inside the performPhaseOnShard method, it creates the shard and sets this newly created span as a parent for the future spans. E.x here

1. performPhaseOnShard for shard B will have parent span as A.
2. performPhaseOnShard for shard C will have parent span as B. Which is wrong and should ideally be A
3. Similarly, performPhaseOnShard for shard C will have a parent span as C.

Describe the solution you'd like
Ideally we need to reset the context in this scenario, so Tracer should provide a new Releasable TracerContext which can be reset to the original one of releasing the current context.

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
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