[web] Optimized images on benchmarks part 2.

...ks/small-deformations/element_deactivation_2D_3D_mesh.png

...benchmarks/small-deformations/element_deactivation_3D.png

web/content/docs/benchmarks/small-deformations/lubby2.png

.../benchmarks/small-deformations/lubby2_creep_over_time.png

...rks/small-deformations/non-equilibrium_initial_states.png

...tent/docs/benchmarks/small-deformations/plasticity_ss.png

...arks/small-deformations/pressure_bc/pipe_axisymmetric.png

...arks/small-deformations/pressure_bc/pipe_plane_strain.png

...s/benchmarks/small-deformations/pressure_bc/sphere_3d.png

...ks/small-deformations/pressure_bc/sphere_axisymmetric.png

...small-deformations/pressure_bc/sphere_axisymmetric_pl.png

...ns/pressure_bc/sphere_axisymmetric_pl_residual_stress.png

...nt/docs/benchmarks/small-deformations/single_joint_3D.png

...chmarks/small-deformations/single_joint_3D_2D_results.png

web/content/docs/benchmarks/small-deformations/ss_load.png

web/content/docs/benchmarks/thermo-mechanics/stress.png

web/content/docs/benchmarks/thermo-mechanics/temperature.png