Replace chromium's product_logo_name for branding

[yrliou]

Right now we're using chromium's product_logo_name images in src/brave/app/theme/default_[100|200]_percent/brave, so we'll see chromium's logo in these cases.
For example,

[srirambv]

Verification Passed on

Brave	0.55.6 Chromium: 70.0.3538.16 (Official Build) dev (64-bit)
Revision	16ed95b41bb05e565b11fb66ac33c660b721f778-refs/branch-heads/3538@{#306}
OS	Linux

Verification PASSED on

Brave	0.55.6 Chromium: 70.0.3538.16 (Official Build) dev (64-bit)
Revision	16ed95b41bb05e565b11fb66ac33c660b721f778-refs/branch-heads/3538@{#306}
OS	Windows

Went through verification using the following build under macOS 10.13.6 x64 - PASSED

Brave	0.55.6 Chromium: 70.0.3538.16 (Official Build) dev (64-bit)
Revision	16ed95b41bb05e565b11fb66ac33c660b721f778-refs/branch-heads/3538@{#306}
OS	Mac OS X

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