Fix lint errors for latest pylint

[woodsp-ibm]

Summary

Fixes to various possibly undefined errors from newest lint

************* Module qiskit_algorithms.gradients.finite_diff.finite_diff_estimator_gradient
qiskit_algorithms/gradients/finite_diff/finite_diff_estimator_gradient.py:144:29: E0606: Possibly using variable 'gradient' before assignment (possibly-used-before-assignment)
************* Module qiskit_algorithms.amplitude_estimators.fae
qiskit_algorithms/amplitude_estimators/fae.py:217:36: E0606: Possibly using variable 'v' before assignment (possibly-used-before-assignment)
************* Module qiskit_algorithms.eigensolvers.vqd
qiskit_algorithms/eigensolvers/vqd.py:286:23: E0606: Possibly using variable 'initial_point' before assignment (possibly-used-before-assignment)
************* Module qiskit_algorithms.time_evolvers.trotterization.trotter_qrte
qiskit_algorithms/time_evolvers/trotterization/trotter_qrte.py:234:33: E0606: Possibly using variable 'single_step_evolution_gate' before assignment (possibly-used-before-assignment)
************* Module test.test_grover
test/test_grover.py:315:15: E0606: Possibly using variable 'grover' before assignment (possibly-used-before-assignment)
************* Module test.time_evolvers.test_trotter_qrte
test/time_evolvers/test_trotter_qrte.py:276:22: E0606: Possibly using variable 'ops' before assignment (possibly-used-before-assignment)

Details and comments

[coveralls]

Pull Request Test Coverage Report for Build 9104207364

Details

• 5 of 5 (100.0%) changed or added relevant lines in 4 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.007%) to 90.619%

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Totals
Change from base Build 8965223889:	0.007%
Covered Lines:	6501
Relevant Lines:	7174

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💛 - Coveralls