Refactor: fix cargo lint failures

[sainad2222]

Fix issues from https://github.com/parseablehq/parseable/actions/runs/16809419242/job/47617200705?pr=1402

1. collapsible_if
   Example:

error: this `if` statement can be collapsed
     --> src/storage/object_storage.rs:890:17
      |
  890 | /                 if let Ok(stats_stream) = PARSEABLE.get_stream(DATASET_STATS_STREAM_NAME) {
  891 | |                     if let Err(err) = stats_stream.flush_and_convert(false, false) {
  892 | |                         error!("Failed in local sync for dataset stats stream: {err}");
  893 | |                     }
  894 | |                 }
      | |_________________^
      |
      = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#collapsible_if
  help: collapse nested if block
      |
  890 ~                 if let Ok(stats_stream) = PARSEABLE.get_stream(DATASET_STATS_STREAM_NAME)
  891 ~                     && let Err(err) = stats_stream.flush_and_convert(false, false) {
  892 |                         error!("Failed in local sync for dataset stats stream: {err}");
  893 ~                     }

2. mismatched_lifetime_syntaxes
   Example:

error: hiding a lifetime that's elided elsewhere is confusing
     --> src/handlers/livetail.rs:276:27
      |
  276 | fn extract_cookie(header: &MetadataMap) -> Option<Cookie> {
      |                           ^^^^^^^^^^^^            ------ the same lifetime is hidden here
      |                           |
      |                           the lifetime is elided here
      |
      = help: the same lifetime is referred to in inconsistent ways, making the signature confusing
      = note: `-D mismatched-lifetime-syntaxes` implied by `-D warnings`
      = help: to override `-D warnings` add `#[allow(mismatched_lifetime_syntaxes)]`
  help: use `'_` for type paths
      |
  276 | fn extract_cookie(header: &MetadataMap) -> Option<Cookie<'_>> {
      |                                                         ++++