[Data] Concurrency cap backpressure with tuning (Disabled) (#59519)

EWMA_ALPHA
Update EWMA_ALPHA from 0.2->0.1. This makes adjusting level to be more in-favor of limiting concurrency by being more sensitive to downstreaming queuing.

K_DEV
Update K_DEV from 2.0->1.0. This makes stddev to be more in-favor of limiting concurrency by being more sensitive to downstreaming queuing.

cherry-pick of #59392

Cherry pick browser request validation improvements (#59045)

Cherry pick #58553 #58648 #59042

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Signed-off-by: Richo Healey <[email protected]>
Signed-off-by: Edward Oakes <[email protected]>
Co-authored-by: richo-anyscale <[email protected]>
Co-authored-by: Lonnie Liu <[email protected]>

change version to 2.52.1 (#59049)

for 2.52.1 release

Signed-off-by: elliot-barn <[email protected]>

[core] Cherry pick token authentication UX improvements (#58831)

Cherry pick: #58737

Signed-off-by: sampan <[email protected]>
Signed-off-by: Edward Oakes <[email protected]>
Co-authored-by: Sampan S Nayak <[email protected]>
Co-authored-by: sampan <[email protected]>

Fixes to tests (#58317)

lint on code format and cherrypick #58215

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Signed-off-by: Lonnie Liu <[email protected]>

[core][cherry-pick] RDT NIXL Limitations + Throw Exception (#58159)

## Description
Cherry-picking #58063 to throw an exception when trying to double send
the same ref before gc because it can trigger a NIXL error. Also adding
documentation for this.

Signed-off-by: Dhyey Shah <[email protected]>
Signed-off-by: Qiaolin-Yu <[email protected]>
Signed-off-by: Qiaolin Yu <[email protected]>
Co-authored-by: Qiaolin Yu <[email protected]>
Co-authored-by: Stephanie Wang <[email protected]>

[cherry-pick] [core] Fix deadlock when cancelling stale requests on i…

…n-order actors (#57746) (#57768)

## Description
Cherry picking #57746

Signed-off-by: dayshah <[email protected]>

[DOC-127] Cherry-pick (#54254): MVP for OSS Ray labels (#57547)

(cherry picked from commit 44a9732)

Co-authored-by: Douglas Strodtman <[email protected]>

2.49.2 version change (#56501)

Signed-off-by: Lonnie Liu <[email protected]>

[data] Cherry pick data fixes for 2.49.1 (#56058)

Cherry pick two fixes for ray data (from
#55854 and
#55926).

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Signed-off-by: iamjustinhsu <[email protected]>
Signed-off-by: Alexey Kudinkin <[email protected]>
Signed-off-by: Matthew Owen <[email protected]>
Co-authored-by: iamjustinhsu <[email protected]>
Co-authored-by: Alexey Kudinkin <[email protected]>