[Tests]Fix md_nsteps in 04_FF (50DP&101NEP)

[ZhouXY-PKU]

Linked Issue

Fix #6873

Unit Tests and/or Case Tests for my changes

• That is a unit test itself.

What's changed?

• md_nsteps are both increased by one due to Add new tests in the integrate tests of LCAO gamma only calculations and update the index to count relax/MD steps, now all steps start from 1, not 0 #6821 (now all steps are start from1, not 0).

Any changes of core modules? (ignore if not applicable)

• No.