docs: remove no longer relevant sections in build page (#43837)
docs: remove no longer relevant sections in build page (#43837)

`Backward compatibility with Lighthouse` and `Backward compatibility with CSS grid` sections are no longer relevant since Internet Explorer is no longer supported.

PR Close #43837

angular/angular,brandonroberts/angular,manekinekko/angular,brandonroberts/angular,angular/angular,shairez/angular,shairez/angular,gnomeontherun/angular,angular/angular,brandonroberts/angular,ocombe/angular,gnomeontherun/angular,gkalpak/angular,ocombe/angular,brandonroberts/angular,gnomeontherun/angular,brandonroberts/angular,angular-indonesia/angular,ocombe/angular,manekinekko/angular,JiaLiPassion/angular,manekinekko/angular,gkalpak/angular,JiaLiPassion/angular,ocombe/angular,shairez/angular,brandonroberts/angular,angular-indonesia/angular,manekinekko/angular,JiaLiPassion/angular,shairez/angular,gkalpak/angular,ocombe/angular,shairez/angular,manekinekko/angular,ocombe/angular,angular/angular,angular-indonesia/angular,gkalpak/angular,JiaLiPassion/angular,manekinekko/angular,angular-indonesia/angular,gnomeontherun/angular