Depcreate Span Queries in favour of Interval Queries

[mayya-sharipova]

Description

Span and Interval queries both have the same function of positional queries to allow control order and proximity of terms.

Interval queries were developed recently and have several benefits over Span queries:

• Simpler interface
• Intervals queries provide scores unlike Span queries
• Interval queries are more performant?

[elasticsearchmachine]

Pinging @elastic/es-search (Team:Search)