Although the phraseology "report landing assured" is not contained in the FAA Air Traffic Control Handbook or the FAA Aeronautical Information Manual, etc., there are circumstances under which specific verbiage/phraseology may be required in accordance with a "Letter of Agreement" (LOA) between a Control Tower and organizations that conduct operations on or near an airport.
For example, an LOA between a helicopter operator and a Control Tower is not uncommon especially at airports with a significant amount of helicopter traffic. This type of LOA reduces radio transmissions, often provides standard routes, altitudes, and procedures for repeated operations.
An example would be the LOA between signatory helicopter operators and the Falcon Field (FFZ) Control Tower located near Phoenix, AZ. See this LOA with attachments HERE. (this FFZ LOA is an example only and may not be current or effective)
Note that in the LOA linked above in paragraph 5.- General Procedures, d., is the following pertinent excerpt containing the phraseology "report landing assured:"
d. Off-airport departures and landings within the FFZ Class Delta Airspace must be
conducted at pilot’s own risk. Pilots must report landing assured at areas within the FFZ
Class Delta Airspace not including Falcon Field Airport. When necessary for
communications, pilots are authorized to climb to 100’ AGL prior to contacting FFZ
(emphasis is mine)
In this LOA the agreed upon phraseology ("report landing assured") is not solicited by the Control Tower, but specified within the LOA.
The phraseology "report landing assured" from BDL Control Tower in the OP's question perhaps might be described and required within an LOA.