chore/release 2.12.0 to develop (#13441)

* Bump version and update CHANGELOG for core v2.12.0

Signed-off-by: Sneha Agnihotri <sneha.agnihotri@smartcontract.com>

* core/services: fix ocrWrapper saveError contexts (#13139)

(cherry picked from commit 15fab1d)

* changed spammy error log to debug (#13153)

(cherry picked from commit 3502176)

* Updating changelog for 2.12.0  with cherry pick fix

Signed-off-by: Sneha Agnihotri <sneha.agnihotri@smartcontract.com>

* BCF-3225 - Implement forwarder fallback if forwarder not present as a transmitter on OCR2 aggregator (#13221)

* Implement forwarder OCR2 fallback if fwd not present as a transmitter

* Add changeset

* Fix panic on mercury server error (#13231) (#13256)

* Fix changelog

* Fixed CPU usage issues caused by inefficiencies in HeadTracker (#13230)

* Fixed CPU usage issues caused by inefficiencies in HeadTracker

* added comments

* revert heads back to the fix

(cherry picked from commit 6f1ebca)

* Update CHANGELOG for 2.12.0 bugfixes

Signed-off-by: Sneha Agnihotri <sneha.agnihotri@smartcontract.com>

* Decouple ChainType from config string [SHIP-2001] (#13272)

* fix: Decouple ChainType from config string

* fix: receiver name and failing test

* test: enhance config test to test for xdai specifically

* refactor: directly unmarshal into ChainType

* fix: validation

* test: fix TestDoc/EVM

* test: add xdai to warnings.xtar

* Index only the fifth word to reduce the db size overhead (#13315)

Co-authored-by: Domino Valdano <domino.valdano@smartcontract.com>

* Add special transmitter for OCR2 feeds (#13323)
* Add special transmitter for OCR2 feeds

* Add ocr2FeedsTransmitter FromAddress()

* Cherry-pick some forwarders context changes from (#13171)

* Improve ocr2FeedsTransmitter FromAddress() fallback (#13343)

* Improve ocr2FeedsTransmitter FromAddress() fallback

* Fix forwarders test error assert

* Update 2.12.0 Changelog with bugfixes

Signed-off-by: Sneha Agnihotri <sneha.agnihotri@smartcontract.com>

* core/services/pipeline: bridge task must continue after cancellation

* core/services/pipeline: use request context for deletion (#13404)

* core/services/pipeline: hide deadline from monitor

* Finalize date on changelog for 2.12.0

Signed-off-by: Sneha Agnihotri <sneha.agnihotri@smartcontract.com>

* Fix merge conflicts

* Remove `overtimeThresholds`

* Return to old version of pipeline-runner

---------

Signed-off-by: Sneha Agnihotri <sneha.agnihotri@smartcontract.com>
Co-authored-by: Jordan Krage <jmank88@gmail.com>
Co-authored-by: Patrick <patrick.huie@smartcontract.com>
Co-authored-by: ilija42 <57732589+ilija42@users.noreply.github.com>
Co-authored-by: Sam <samsondav@protonmail.com>
Co-authored-by: Dmytro Haidashenko <34754799+dhaidashenko@users.noreply.github.com>
Co-authored-by: Friedemann Fürst <friedemann.fuerst@smartcontract.com>
Co-authored-by: Mateusz Sekara <mateusz.sekara@smartcontract.com>
Co-authored-by: Domino Valdano <domino.valdano@smartcontract.com>
Co-authored-by: ilija <pavlovicilija42@gmail.com>
Co-authored-by: frank zhu <fr@nkzhu.com>
Co-authored-by: george-dorin <george.dorin@smartcontract.com>