FLAG-69: Improve the performance of patient flag evaluation

[ManojLL]

Description of what I change

change to evaluate patient flags in parallely on generateFlagsForPatient(...) method.

Issue Worked On

worked on FLAG-69

Test

use the method execution time in milliseconds (ms) to evaluate the performance.
Generate flags for patient

Generate flags for patient
parallel process -> 7.6.5.8,7,7,6,7,8,6 => avg 6.7 milliseconds

current module -> 8,7,7,6,8,7,7,7,8,6 => avg 7.1 milliseconds

flags count < 5 - current module perform better than this implementations
flags count < 10 - both are perform in same way
flags count = 17 - this implementation perform better than current module

when the flag count is increased, the prell process performs better than the current module.

method test : generate flags for patient : FalgServiceImpl.generateFlagsForPatient(Patient patient, Context)

[wikumChamith]

@ManojLL can you fix the merge conflicts?

[wikumChamith]

Can we switch to streams here?

[ManojLL]

updated the code with forEach

[wikumChamith]

why did you remove the null check here?

[ManojLL]

in this line , I initialized the executor as a thread pool. If the generateFlagForPatient method is called first, the executor is already initialized as thread pool, so then evaluateAllFlags uses a thread pool instead of a single thread. after removing the null check when evaluateAllFLag method calls it initialize the executor as a single thread.