title: Modifying beamer's frame title template to change head/foot text colors for title page only
body: <p>Im building a beamer template for my university with a customized <code>frame title</code> template and I would like to have the <code>author</code>, <code>title</code> and <code>institute</code> fields displayed in the footline of all frames except in title page.</p>
  <p>Following <a href="https://tex.stackexchange.com/questions/338856/beamer-change-titlepage-not-to-show-details-in-headline-footline">this</a> discussion, I manage to do that by locally setting the footline font color equal to the footline background color in the title frame.</p>
  <p>Even though this solution produces the output that I want, I would like to know if there is any way to obtain the same output by modifying the <code>frame title</code> template instead, so that all the customizations happen in the preamble.tex file.</p>
  <h2>MWE:</h2>
  <h3>main .tex file</h3>
  <pre class="lang-tex prettyprint-override"><code>\include{preamble}
  
  \title{presentation-title}
  \author{my-name}
  \date{\today}
  
  \begin{document}
  
  {
  \setbeamercolor{author in head/foot}{use=palette secondary, fg=palette secondary.bg} 
  \setbeamercolor{title in head/foot}{use=palette tertiary, fg=palette tertiary.bg} 
  \setbeamercolor{institute in head/foot}{use=palette secondary, fg=palette secondary.bg} 
  \frame{\titlepage}
  }
  
  \begin{frame}
      frame content
  \end{frame}
  
  \end{document}
  </code></pre>
  <h3>preamble.tex file:</h3>
  <pre class="lang-tex prettyprint-override"><code>
  \documentclass{beamer} 
  
  % Theme and sub theme 
  %--------------------------------------------------------------
  \usetheme{Berlin}                             
  \usecolortheme{beaver}       
  
  % Global color settings
  %--------------------------------------------------------------
  \definecolor{Maroon}{cmyk}{0, 0.87, 0.68, 0.32}
  
  \setbeamercolor{author in head/foot}{fg=Maroon}     
  \setbeamercolor{institute in head/foot}{fg=Maroon}  
  \setbeamercolor*{title}{fg=white, bg=Maroon}          
  
  % Modified title page template
  %--------------------------------------------------------------
  \setbeamertemplate{title page}{
  
  \insertauthor
  
  \insertinstitute
  
  \inserttitle
  
  }
  </code></pre>