break: drop `module.GetShare` at some point

[cristaloleg]

Implementation ideas

Based on comment https://github.com/celestiaorg/celestia-node/pull/3891#discussion_r1849677926

CC: @Wondertan

[rootulp]

Notes from call:

• This isn't just a deprecate + remove. It's a new method.
• GetSamples accepts different arguments and returns different values.
• GetSamples returns proofs.
• Do users use GetShare?
  • Can we get metrics on usage? We have some indirect metrics that we can collect.
  • Can we get signal from Diego or RollKit? Diego already shared which endpoints are used. See doc. GetShare isn't really used.
• Another method exists: GetRange so GetShare may not be used much.